ChatGPT vs Gemini vs Claude vs Copilot: which AI to use for which office task

No single tool is best at everything. If your company runs on Microsoft 365, Copilot sits inside Word, Excel and Outlook; if you live in Gmail and Google Docs, Gemini is more tightly built in. ChatGPT and Claude are standalone apps, and Claude Pro includes the Claude Code programming tool. All four can be used in Vietnam.

This guide is compiled from the four vendors' official pricing and help pages and the VOZ forum. Dùng Gì did not run its own tests or score the tools; community opinions are labelled as such. Every figure was checked on 27 September 2026, so re-check the vendor's page before you pay.

Where the four tools differ

The biggest difference between the four is the ecosystem each one is attached to:

• ChatGPT (OpenAI) is a standalone app. The free plan includes web search, file uploads, image generation and deep research, all with limits; there are extensions for Excel, Word, PowerPoint and Google Sheets.
• Gemini (Google) is tied to your Google Account. From the Google AI Plus plan upwards, Gemini appears in Gmail, Docs and other Google apps, along with shared cloud storage.
• Claude (Anthropic) is a standalone app. The free plan includes web search, file creation and code execution; Pro adds Research, full Projects (the free plan allows up to 5), Claude Code and Claude for Microsoft 365.
• Microsoft Copilot comes in two forms: the free Copilot app, and Copilot inside Word, Excel, PowerPoint and Outlook with a Microsoft 365 Personal, Family or Premium subscription. Businesses can add Microsoft 365 Copilot as an add-on.

Still choosing an office suite for your company? Read Microsoft 365 vs Google Workspace for small businesses first, because that choice largely decides which AI assistant is most convenient.

Quick comparison by task

The table is based on the feature lists on the official pricing pages, not on test results: "yes" means the vendor lists the feature, not that every tool does it equally well.

Which tool for which job

Choose Copilot if your company already uses Microsoft 365 and most of your work happens in Word, Excel, Outlook and Teams: Copilot works inside the file you have open, with no copying and pasting back and forth. Personal plans are different from Microsoft 365 Copilot for business.

Choose Gemini if you mostly work in Gmail, Docs, Sheets and Drive. The free plan already includes Deep Research and image generation; paid plans add Gemini in Gmail and Docs plus storage.

Choose ChatGPT if you want one standalone tool for many kinds of work, independent of your office suite. The Go plan is the cheapest but may include ads.

Choose Claude if you often work with long documents (contracts, reports, technical documentation) or code: the pricing page lists a context window of up to 1M tokens depending on the model, and Claude Code comes with Pro. The free plan has no Research and a limit of 5 Projects.

For Excel, AI helps you write formulas faster, but you still need the basics to check the result; if you are not there yet, see the Excel learning path for office staff.

You don't have to pick just one: you can use the free versions of several tools and pay only for the one you open every day.

Free and paid plans (checked 27 September 2026)

Prices are copied exactly from the official pricing pages, in the currency each vendor shows when viewed from Vietnam, without conversion. Prices through the App Store or Google Play may differ.

ChatGPT (chatgpt.com/pricing, shown in Vietnamese dong):

• Free: ₫0 / month.
• Go: ₫132,000 / month, with more messages, uploads and image generation; may include ads.
• Plus: ₫522,500 / month, adding reasoning models, Projects and custom GPTs.
• Pro: from ₫2,849,000 / month.
• Business (from 2 users): Standard seat ₫519,000 / month billed annually, ₫649,000 / month billed monthly.

Gemini (gemini.google/subscriptions, shown in VND):

• Free: ₫ 0 VND/month, requires a Google Account.
• Google AI Plus: ₫ 132.000 VND/month, 2x the free plan's limits, 400 GB storage, Gemini in Gmail and Docs.
• Google AI Pro: ₫ 489.000 VND/month, 4x the limits, 5 TB storage.
• Google AI Ultra: from ₫ 2.250.000 VND/month.

Claude (claude.com/pricing, shown in US dollars, excluding tax):

• Free: $0.
• Pro: $17 per month with an annual subscription ($200 billed up front), or $20 billed monthly.
• Max: from $100 per month, 5x or 20x the usage of Pro.
• Team: Standard seat $20 per user per month billed annually, $25 billed monthly.

Microsoft Copilot (Microsoft Vietnam's Microsoft 365 comparison page):

• Copilot app: free.
• Microsoft 365 Personal: 210.000,00 ₫/month or 2.099.000,00 ₫/year, including Copilot in Word, Excel, PowerPoint and Outlook.
• Microsoft 365 Family: 260.000,00 ₫/month or 2.599.000,00 ₫/year; AI features are for the subscription owner only.
• Microsoft 365 Premium: 510.000,00 ₫/month or 5.099.000,00 ₫/year, with higher Copilot limits and advanced research.

Vendors describe limits in words ("limited", "2x", "5x") rather than message counts; Anthropic states explicitly that usage depends on conversation length, model and features.

Google is giving eligible students 12 months of Google AI Plus, claimable until 31 December 2026 — eligibility and steps are in our Gemini Pro for students guide.

Vietnamese: what vendors say, what the community says

Microsoft's support page (updated February 2026) lists Vietnamese among the languages Copilot supports. Dùng Gì found no official publication comparing Vietnamese-language quality across the four tools.

On VOZ, impressions vary widely: some users found Gemini's explanations more detailed, one suggested Claude for translation, another complained that a tool kept making calculation errors. These are personal opinions from 2024–2025, with older models than today's. The most reliable approach: take a real task (a tricky email, a report to summarise), ask several tools on their free plans, and compare for yourself.

In the 2024 thread, one user also pointed out that AI does not always answer correctly. For work documents, numbers, clauses and citations always need checking against the original source.

Work data: which settings to turn on

Personal accounts (free and individual paid plans):

• ChatGPT: go to Settings, Data controls and turn off "Improve the model for everyone" so new conversations are not used to train models. Temporary chats do not appear in history and are not used for training, but may be kept for up to 30 days for safety purposes.
• Claude: Anthropic uses chats to improve its models only if you allow it in Privacy Settings (or if a conversation is flagged for safety review). Incognito chats are not used. When you give thumbs up/down feedback, the whole conversation is stored as feedback for up to 5 years.
• Gemini: Google's human reviewers may see some conversations. To avoid this, turn off "Keep Activity" or use temporary chats (still kept for 72 hours). Conversations already reviewed are not deleted when you delete your activity.
• Personal Copilot: you can opt out of your conversations being used for model training; activity is stored for 18 months by default.

Work accounts:

• ChatGPT Business and Enterprise: no training on business data by default.
• Claude Team and Enterprise: no model training by default.
• Gemini with a Google Workspace account: content is not human-reviewed or used for training outside your organisation without permission.
• Microsoft Copilot with a work account: prompts, responses and data accessed through Microsoft Graph are not used to train foundation models.

If your company allows AI with internal documents, use the account your company provides. Avoid "shared accounts" or accounts not in your own name sold online: you cannot know who can read your chat history.

Can you use them in Vietnam?

Yes. Vietnam is on the supported-countries list for ChatGPT (OpenAI Help Center) and for Claude.ai (Anthropic's page). Gemini's pricing page shows prices in VND when viewed from Vietnam, and Microsoft sells Microsoft 365 plans with Copilot on its Vietnamese site. According to Microsoft, the Copilot app is available in more than 170 markets, with exceptions such as mainland China.

Vietnam is on ChatGPT's list of supported countries, and OpenAI's pricing page shows every plan, including Go, in đồng when viewed from Vietnam. ChatGPT and Claude accept credit cards; companies that need invoices should ask the vendor's sales team.

Frequently asked questions

Should I get ChatGPT Plus or Gemini Pro?

It depends on where you work. If you use Gmail, Docs and Drive daily and need more storage, Google AI Pro bundles both. If you need a standalone assistant with Projects, custom GPTs and Excel extensions, ChatGPT Plus fits better. Try the free versions of both first.

Is ChatGPT Plus or Claude Pro better for writing?

No official source compares them directly. Claude Pro offers Research, Claude Code and Claude in Microsoft 365; ChatGPT Plus offers image generation, deep research and custom GPTs. Try the same writing task on the free plans of both.

Is it safe to put company documents into AI?

Only if your company allows it, and preferably through a work account (ChatGPT Business, Claude Team, Gemini in Workspace, Copilot with a work account), because these plans do not use your data for model training by default. On a personal account, turn off the training option as described above.