Comprehensive Comparison of Major LLMs: A Guide to Using ChatGPT, Perplexity, Grok, and Gemini

1. Introduction

In recent years, the evolution of generative AI has been remarkable, especially large language models (LLMs: Large Language Models), which have been increasingly implemented across various industries for tasks such as improving work efficiency, information gathering, and planning. New models are emerging daily, and while options like ChatGPT, Gemini, Perplexity, and Grok are expanding, there are also many situations where users find themselves wondering "Which one should I use?" or "Which one best fits my purpose?".

This article introduces the major LLMs by comparing their features, functions, and usability, and recommends models based on different use cases. Rather than advocating for a specific tool, it focuses on making it easier to choose based on "what purpose you want to use it for." We hope this will be helpful for those who are trying to incorporate LLMs into their work for the first time or those who want to try using multiple models.

2. Overview of Major LLMs

This article briefly introduces the four LLMs covered.

ChatGPT (OpenAI)

ChatGPT is a large language model developed by OpenAI and is currently one of the most well-known LLMs used by many companies and individuals. The model is continuously updated as part of the "GPT" series, steadily evolving in terms of naturalness of dialogue, response accuracy, and processing speed. It excels at natural conversation and document generation, with an intuitive interface, making it widely supported as an introduction to generative AI. Additionally, through a partnership with Microsoft, integration with Office products (such as Word and Excel) and the Azure OpenAI Service for business use is progressing.

Additionally, the paid plans offer flexibility suitable for business use, including access to high-performance models (GPT-4 series), plugins, and custom GPTs. The top-tier paid plan, the Enterprise Plan, provides security features and management functions tailored for companies, designed with full-scale business utilization in mind.

Gemini (Google)

Gemini is a multimodal generative AI developed by Google DeepMind, evolved from the former "Bard" series. It is built on Google Search technology and its strong integration with other Google services (such as Gmail, Google Docs, YouTube, etc.) is a key strength. Gemini features multimodal capabilities that handle not only text but also images and PDFs, with its range of support expanding through continuous updates from Google. This enables it to, for example, read PDF-format meeting materials to create summaries or generate reports including charts and tables, thus supporting documents containing information beyond just text.

Additionally, by linking with a Google account, users can access information and settings tailored to their environment, making it highly convenient for both personal and business use. For users who prioritize compatibility with Google products, it can be considered a strong option that allows for natural adoption and integration.

Perplexity (Perplexity AI)

Perplexity is an AI service characterized by its style of providing answers while searching and referencing real-time web information. It responds to user questions by presenting multiple related sources and summarizing the key points, making it suitable as a reliable information-gathering tool with cited references. Since answers clearly indicate source information such as URLs and article titles, it is a major strength that users can quickly obtain data backed by evidence for business or research purposes.

Furthermore, the paid plan allows users to switch between multiple advanced LLMs such as GPT-4 and Claude 3, enabling model selection according to the purpose. Responses in Japanese are also stable, with outputs that concisely summarize key points and have a clear sentence structure, which is well received. Perplexity's unique approach, combining search functionality and summary generation, makes it a powerful tool for business professionals and researchers who want to efficiently organize information.

Grok (xAI)

Grok is an interactive AI developed by xAI, led by Elon Musk, and is notably built with integration into the social media platform X (formerly Twitter) in mind. It particularly excels in accessing highly real-time information such as trending topics and user posts that are posted daily on X, giving it strong capabilities in understanding and responding to current events. Because it provides responses that take into account the flow of information centered on social media, it is also expected to be useful for trend analysis and marketing purposes.

Additionally, compared to other LLMs, its conversational style often includes casual and humorous outputs, making it a user-friendly design for those who want to enjoy more natural and human-like interactions. It is expected to become even more refined as xAI’s proprietary model in the future, representing a presence that suggests new possibilities for generative AI centered on integration with social media platforms.

3. Features, Strengths, and Weaknesses of Each LLM

The results of comparing each model in terms of performance and features are summarized below.

Item	ChatGPT	Gemini	Perplexity	Grok
Developer	OpenAI	Google DeepMind	Perplexity AI	xAI
Accuracy and Stability of Responses	Outputs natural Japanese in both grammar and tone, suitable for business documents	Enables smooth Japanese output leveraging Google Translate technology	Skilled at concisely summarizing key points in accurate Japanese	Able to naturally handle casual and colloquial Japanese expressions
Research and search integration	Integration with Bing (from Plus plan onwards)	Information reference based on Google Search available	Capable of providing sourced answers based on web search	Strong in current topics through SNS integration
Diversity of output formats	Supports text, code, images, etc.	Supports text, images, PDFs, etc.	Text-focused, strong at summarizing key points	Text-focused, also supports SNS-style writing
User experience & UI	Simple UI designed for general users	UI with a unified feel of Google products	A simple screen layout displaying answers with sources in a list	Design integrated with X (formerly Twitter)
Examples of use cases	Creating project proposals, summarizing, document generation	Reading multiple documents, multimodal analysis	Research, organizing information with sources	Trend research, post support

4. Comparison of Pricing Structures and Usage Restrictions (As of June 2025)

Many LLMs can be started for free, but some require payment to use high-performance models. Below is a comparison of the main pricing structures.

LLM	Availability of Free Plan	Paid Plan (Reference)	API Availability	Main Limitations of Free Version
ChatGPT	Available	Plus: $20 per month	Available	Restrictions on response accuracy and speed during high load
Gemini	Available	Advanced: 2,900 yen per month	Available	Answer accuracy and other feature limitations apply
Perplexity	Available	Pro: $20 per month	Available	High-precision model limited to 5 times per day (standard model has no usage limit)
Grok	Available (up to 10 times every 2 hours)	SuperGrok: $30 per month	Available	Restrictions on advanced features (DeepSearch mode and Think mode)

5. Recommended LLMs by Use Case

■Business Use (Data Analysis, Presentation Creation, Team Collaboration): ChatGPT

ChatGPT is useful when you want to quickly draft reports or proposals, or when you want to organize meeting notes and minutes into a polished form. It can generate natural and easy-to-read Japanese and excels in logical structure, making it suitable for situations where business documents need to be completed in a short time.

Also, if you specify the format and tone in advance, it will organize the document accordingly, making it convenient when you want to unify the document style within the team. By creating a custom GPT, it is also possible to provide responses that reflect internal rules and terminology.

■Information Search and Fact-Checking: Perplexity

Perplexity is invaluable when you want to grasp market trends or research a specific topic with evidence. It answers questions by referring to the latest information on the web with sources cited, allowing you to verify "where this information came from" while preparing research materials or reports.
When you want to investigate complex topics from a comprehensive perspective, you can utilize the Deep Research feature to obtain organized answers from multiple related viewpoints. It excels in situations where you need to balance accuracy and speed in information gathering.

■Real-time Information and Social Media Analysis: Grok

Grok is useful when you want to quickly grasp trending topics on social media or monitor reactions to your brand or services. It is integrated with X (formerly Twitter), making it easy to capture trends and user responses in real time, which is ideal for situations requiring time-sensitive decisions.
For example, during a campaign, analyzing "which types of posts are increasing" or "how user evaluations are changing" can help adjust marketing strategies and review PR policies.

■Security-Focused Use Cases (Handling Confidential Data): ChatGPT

When you want to use LLMs for tasks involving highly confidential data such as customer information or contract data, ChatGPT's Enterprise Plan (paid) provides peace of mind. It complies with regulations like GDPR and HIPAA and meets the information protection standards required for business operations.
Especially in industries requiring strict compliance, such as healthcare, finance, and legal sectors, it is important to choose an LLM with robust security measures. This is an appropriate choice when you want to establish a system to safely utilize generative AI within your organization.

■Document Processing and Multimodal Support: Gemini

For example, Gemini is useful when you want to load and summarize meeting materials in PDF format or organize and explain the contents of reports that include charts and tables. Its multimodal capabilities come into play when organizing information across multiple files or reading and processing materials that include images and layouts.
Additionally, since it can be integrated with Google services such as Gmail, Google Drive, and Calendar, it functions especially efficiently in work environments that regularly use Google Workspace. When you want to handle everyday tasks, where information tends to be scattered, through a single interface, Gemini is a strong option.

Note:
The performance of each LLM depends on the user's needs and usage environment. Please check the official websites for the latest features and pricing.

ChatGPT
Gemini
Perplexity
Grok

6. Summary

The major LLMs—ChatGPT, Gemini, Perplexity, and Grok—each have different development backgrounds, areas of expertise, and usage policies. Rather than just using a popular LLM by default, choosing a model that fits your specific goals and work can greatly impact productivity.
Especially when considering business use, careful selection including factors such as price, security, and data handling policies is crucial. We hope this article serves as a helpful guide when incorporating LLMs into your work.