ChatGPT vs Microsoft Copilot: Comparison and Functionalities

ChatGPT works as a standalone assistant, while Microsoft Copilot is built (also) into Microsoft 365 apps.

ChatGPT handles more general tasks; Copilot focuses on Office and coding work.

ChatGPT allows more custom setup and API use; Copilot connects better with company data.

ChatGPT has flexible pricing; Copilot costs a flat monthly fee per user.

1. Underlying Technology & Architecture

GPT-4o (“Omni”) has been the default ChatGPT model since April 30, 2025, supporting text, vision, and audio with a 128 K-token context window and powering plugins, Advanced Data Analysis, and image generation . On April 14, 2025, OpenAI released the GPT-4.1 family in its API—Main, Mini, and Nano variants—each supporting up to 1 million tokens of context, offering ~26 % better reliability and ~26 % lower per-token cost compared to GPT-4o . Public analyses estimate GPT-4 at ~1.8 trillion parameters, while GPT-4.1 focuses on inference efficiency and long-context attention optimizations rather than raw scale .

Microsoft 365 Copilot embeds GPT-4 via Azure OpenAI Service within a three-component system—UI, LLM, and Microsoft Graph Data Connectors—for real-time grounding in enterprise content. Copilot applies enterprise-grade security and tenant isolation, and Microsoft plans to introduce proprietary “MAI” models once they reach production parity .

ChatGPT helps users directly by answering questions, analyzing data files, translating texts, and debugging code—all within a simple chat interface.

Microsoft 365 Copilot is built into Office apps like Word, Excel, and Teams, where it drafts documents, summarizes meetings, and builds Excel reports based on your company’s own information.

GitHub Copilot integrates into coding environments, automatically completing code, explaining snippets, and quickly solving coding problems, significantly speeding up software development tasks.

2. Core Capabilities & Supported Workloads

ChatGPT (GPT-4o & API)

• General language: Summarizes documents, translates between 70+ languages, answers queries, drafts emails and essays in one chat interface .

• Data analysis & coding: Advanced Data Analysis (formerly Code Interpreter) runs Python on uploaded files to produce statistics, charts, and debug sessions within chat .

• Multimodal: Processes images for captioning and diagram interpretation, and supports voice I/O via integrated TTS/STT .

Microsoft 365 Copilot

• Office integration: Drafts and refines Word documents, builds complex Excel models (PivotTables, formulas), designs PowerPoint slides with speaker notes, and auto-summarizes Outlook threads and Teams meetings—all powered by GPT-4 on Azure .

GitHub Copilot

• IDE assistance: Provides line- and function-level code suggestions in VS Code, JetBrains, and Neovim; offers a chat pane for iterative Q&A; studies show ~50 % faster task completion and reduced cognitive load .

3. Integration & Ecosystem

ChatGPT provides easy-to-use APIs and a wide selection of plugins through its GPT Marketplace, allowing developers to connect ChatGPT with external services and data sources for customized uses.

Microsoft 365 Copilot integrates tightly within the Microsoft 365 environment, using Microsoft Graph Data Connectors to pull real-time data from your company's emails, documents, and chats, enabling highly personalized responses inside familiar tools.

GitHub Copilot works directly within popular coding editors and currently does not provide a public API or plugin system; instead, its features are seamlessly embedded in tools like VS Code, JetBrains IDEs, and Neovim for immediate coding support.

APIs & SDKs

• OpenAI API: RESTful chat and completions endpoints, with official libraries (e.g., openai for Python) and community SDKs; rate limits vary by plan .

• Microsoft 365 Copilot: Extensible via Teams Toolkit—declarative API plugins defined with OpenAPI specs—and Microsoft Graph Data Connectors; no public LLM REST API .

• GitHub Copilot: Delivered exclusively through editor extensions; lacks a standalone API .

Platform Embedding

• ChatGPT for Teams & Enterprise: Centralized workspaces with SSO, audit logs, billing controls, plus desktop/mobile apps and Azure deployment options .

• Microsoft 365 Copilot: Built into Word, Excel, PowerPoint, Outlook, and Teams; “Copilot in Teams” replaces any standalone chat UI .

• GitHub Copilot: Integrates directly into IDEs, surfacing suggestions inline and via chat pane.

Extensibility

• GPT Marketplace & Builder: Over 150 vetted plugins and a no-code “GPT Builder” interface for creating custom GPTs, discoverable under “Explore GPTs” .

• Copilot Studio (Preview): Lets makers combine actions and Data Connectors to build custom agents; Power Platform connectors extend Copilot to services like Salesforce, ServiceNow, and Azure SQL .

4. Performance & Quality Metrics

Automated Benchmarks

• MMLU: GPT-4.1 scores ~90.2 %, GPT-4o ~85.7 %, GPT-4.1 mini ~80.1 % .

• HumanEval: GPT-4.1 achieves ~52.8 % pass@1, GPT-4o ~51.5 %; Codex base model scored 28.8 %, “cushman-ml” variant 56.1 % .

Human Evaluation

• GPT-4.1 ranks in the top 10 % on a simulated U.S. bar exam and scores 86.7 % on USMLE-style questions .

• 90 % of developers report greater fulfillment and 95 % more enjoyment when using GitHub Copilot .

Latency & Throughput

• GPT-4o: ~0.71 s first-token latency, ~44.5 tokens/s throughput; GPT-4.1 matches or slightly exceeds these figures in batch API calls .

• Azure-backed Copilot: optimal TCP latency < 10 ms (degraded above 25 ms) and endpoint latency < 250 ms recommended for fluid responses .

5. Prompting & Customization

Prompt Engineering

• Zero- and few-shot with exemplar prompts, chain-of-thought (“think step by step”), and system messages (“You are a concise technical assistant”) enhance accuracy and consistency .

• Iterative A/B testing across model versions and safety-oriented system prompts refine outputs for enterprise deployments .

End-User Controls

• Custom Instructions: Persistent settings for tone, format, and role applied automatically to new chats .

• Memory: Retains user-specified details and past interactions across sessions, with full controls to view, delete, or disable .

• GPT Builder: No-code creation of specialized agents, accessible via the GPT Marketplace .

• Copilot Toggles & Flags: Users enable or disable Copilot per app; IT admins configure feature flags (e.g., image generation, connector access) centrally in the Microsoft 365 admin center .

6. Reliability, Safety & Hallucinations

Error Tendencies

• ChatGPT’s hallucination rate reaches ~10–15 % in medical systematic reviews, particularly when generating citations .

• GitHub Copilot may introduce insecure or semantically incorrect code; up to 30 % of suggestions carry vulnerabilities without SAST and peer review safeguards .

Mitigation Strategies

• RLHF enhanced by CriticGPT improves trainer evaluation accuracy by ~63 % .

• The Moderation API filters or blocks unsafe content .

• Retrieval-Augmented Generation via plugins or Data Connectors grounds outputs in up-to-date data .

• “Semantic entropy” detectors flag hallucinations with ~79 % accuracy, though adoption remains limited .

Data Protection

• ChatGPT retains API data for up to 30 days (opt-out available) and auto-expires uploaded files after 48 hours for Enterprise users .

• Microsoft 365 Copilot encrypts data at rest/in transit, isolates tenant content, and does not use enterprise prompts for model training; compliant with GDPR, HIPAA, SOC 2, and ISO standards .

7. Cost & Licensing

ChatGPT Plans

• Free: GPT-3.5 access and limited GPT-4o usage.

• Plus: $20 /mo; priority GPT-4o access and Advanced Data Analysis .

• ChatGPT for Teams: $25 /user /mo (annual) or $30 /user /mo (monthly); team collaboration, admin controls, no data-training on team chats .

• Enterprise: Custom pricing; unlimited GPT-4o, SSO, audit logs, enhanced security .

API Usage (GPT-4.1 Series)

• GPT-4.1: $2.00 /1 M input tokens; $8.00 /1 M output tokens (blended $1.84) .

• GPT-4.1 mini: $0.40 /1 M input; $1.60 /1 M output.

• GPT-4.1 nano: $0.10 /1 M input; $0.40 /1 M output.

GitHub Copilot

• Free: 2 000 completions + 50 chats /mo.

• Pro: $10 /mo or $100 /yr; unlimited suggestions and chat .

• Business: $19 /seat /mo; team policies and admin features .

• Enterprise: $39 /seat /mo; SAML SSO, SCIM, audit logs, private extensions .

Microsoft 365 Copilot

• Add-on: $30 /user /mo on qualifying Microsoft 365 plans, billed annually; includes Copilot in Word, Excel, PowerPoint, Outlook, and Teams .

• Volume-license agreements via reseller may yield additional discounts at scale.