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TL;DR:
- GPT‑5 is now the default model for all ChatGPT tiers, offering top-tier reasoning, safer responses, and unmatched performance across writing, coding, and enterprise use.
- GPT‑4o remains the best for voice-first, real-time chat experiences, thanks to emotional expression and multimodal responsiveness.
- OpenAI o3 is being phased out, but was previously used for advanced agentic tasks in developer workflows.
- GPT‑5 outperforms both GPT‑4o and o3 across all major benchmarks, including coding (SWE-bench), video reasoning, and health-related queries.
- Choosing the right model depends on your goals and plan tier, but GPT‑5 now powers most tools and is ideal for enterprise-grade AI solutions.
Introduction
OpenAI has once again pushed the boundaries of artificial intelligence with the release of GPT‑5—a unified, safety-first model designed to deliver PhD-level reasoning and real-world utility. But with GPT‑4o still popular for chat and voice use, and OpenAI o3 having powered many developer and enterprise workflows, choosing the right model in 2025 isn’t so straightforward.
In this guide, we break down the differences between GPT‑5, GPT‑4o, and o3—comparing reasoning capabilities, safety, multimodal features, and ideal use cases. Whether you’re a developer, startup founder, or enterprise evaluating AI integration, this comparison will help you make an informed decision. If you’re looking to build solutions powered by the latest models, partnering with an experienced OpenAI development company can ensure you’re leveraging the best model for your goals.
Meet the Models
| Model | Released | Purpose |
| GPT‑4o | May 2025 | Fast, expressive, multimodal model for chat/voice use |
| OpenAI o3 | Late 2024 | High-reasoning model for devs and enterprise users |
| GPT‑5 | August 2025 | Unified, safety-optimized model with expert-level reasoning |
Each model reflects OpenAI’s evolving priorities: GPT‑4o focused on speed and humanlike interaction; o3 emphasized reasoning and tool use; and GPT‑5 unifies the best of both worlds—while setting new safety, accuracy, and reasoning standards.
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Key Comparison Areas
To help you decide which model suits your needs, we’ve broken down the core differences across performance benchmarks, multimodal strengths, safety standards, and ideal use cases. This side-by-side view gives you a clear picture of how GPT‑5, GPT‑4o, and o3 stack up in 2025.
Performance & Reasoning
GPT‑5 dominates across benchmarks. On the AIME 2025 math test, it scored 94.6%, compared to GPT‑4o’s 71% and o3’s 88.9%. In software engineering, GPT‑5 achieved 74.9% on SWE-bench Verified, far outperforming GPT‑4o (30.8%) and o3 (52.8%).
Its new reasoning engine allows it to understand nuance, follow complex instructions, and provide structured outputs more effectively than any prior model. For example, GPT‑5 can now generate an entire health rehabilitation plan or draft legal documents with minimal prompting.
Multimodal Capabilities
GPT‑4o remains the king of voice-first experiences—offering real-time interaction with emotional tone and expressive responses. It’s the only model to support live audio, making it great for hands-free usage and storytelling.
GPT‑5, while not built for real-time voice, excels at visual and video-based tasks. It achieved 84.2% on the MMMU benchmark and 81.1% on VideoMMMU, making it ideal for analyzing charts, UI mockups, or video summaries.
o3 supports basic image understanding but lacks the depth or speed of the other two.
Safety & Reliability
GPT‑5 introduces safe completions, which respond to risky or underspecified prompts with helpful, bounded answers instead of full refusals. It also has the lowest hallucination rate ever recorded in OpenAI’s production traffic: only 2.1% of GPT‑5’s reasoning responses contained factual errors, compared to 4.8% for o3.
It also significantly reduces sycophancy and deceptive completions. In multimodal safety tests (like being asked about missing images), GPT‑5 answered honestly just 9% of the time—vs 86.7% for o3.
Best Use Cases by Model
- GPT‑5: Writing complex documents, coding across large repos, health and legal advice, enterprise automation
- GPT‑4o: Voice chat assistants, emotional storytelling, creative brainstorming in real time
- o3: Legacy agent tasks with browser/tool use—now mostly replaced by GPT‑5 Pro
By aligning each model to its performance strengths, developers and businesses can deploy the right AI engine for their needs—whether that’s reasoning through 100-page contracts or narrating bedtime stories in real time.
Comparison Table
| Feature/Metric | GPT‑5 | GPT‑4o | OpenAI o3 |
| AIME 2025 (Math) | 94.6% | 71% | 88.9% |
| SWE-bench Verified (Coding) | 74.9% | 30.8% | 52.8% |
| VideoMMMU (Video reasoning) | 81.1% | 58.8% | 57.8% |
| HealthBench (Hard health Qs) | 46.2% | 31.6% | 25.5% |
| Hallucination Rate (prod traffic) | 2.1% | ~3.6% (est.) | 4.8% |
| Deceptive Response Rate | 9% | ~12% (est.) | 86.7% |
| Real-time Voice Support | ❌ | ✅ | ❌ |
| Emotional Expression (Voice) | ❌ | ✅ | ❌ |
| Safe Completions (for risky prompts) | ✅ | ❌ | ❌ |
Ideal Use Cases: Which Model Excels Where?
Each model shines in different scenarios. Here’s where each stands out with examples:
- GPT‑5: Ideal for knowledge-intensive and mission-critical tasks. It excels at drafting research papers, legal documents, and in generating complete codebases. Enterprises can use it to automate internal workflows or build AI agents that need accuracy, logic, and adaptability.
- GPT‑4o: Best for real-time, voice-based interactions and content creation. Perfect for building virtual assistants, AI tutors, and storytelling apps where tone, emotion, and immediacy matter. For example, it’s great for narrating children’s stories or answering spoken queries.
- OpenAI o3: Previously used for pro-level reasoning and agent tasks. Developers used o3 for tool-rich environments and task planning, such as coordinating data analysis tools or web agents. It’s now mostly phased out in favor of GPT‑5 Pro.
By aligning your project with the right model, you’ll get the best results—whether it’s building a fast customer-facing bot or launching a deep-reasoning enterprise AI system.
- GPT‑5: Writing complex documents, coding across large repos, health and legal advice, enterprise automation
- GPT‑4o: Voice chat assistants, emotional storytelling, creative brainstorming in real time
- o3: Legacy agent tasks with browser/tool use—now mostly replaced by GPT‑5 Pro
By aligning each model to its performance strengths, developers and businesses can deploy the right AI engine for their needs—whether that’s reasoning through 100-page contracts or narrating bedtime stories in real time.
Which Model Should You Use?
Your ideal OpenAI model depends on your usage needs and budget. Here’s how each option stacks up:
- Free Users (Free): Now get GPT‑5 (GPT‑5-mini) by default — a major upgrade over GPT‑4o. You get basic access to high-quality reasoning, with light usage limits.
- Plus Users ($20/month): Unlock full access to GPT‑5 with higher limits. Perfect for creators, professionals, and AI enthusiasts who want consistent access to smarter, faster completions.
- Pro Users ($60/month): Gain access to GPT‑5 Pro, designed for developers and advanced users building agentic workflows, tools, and apps. Ideal for startups and tech teams who want the best performance for reasoning-heavy tasks.
- Enterprise Teams (Custom Pricing): Use GPT‑5 via ChatGPT Team, Azure AI, or Codex CLI. Enterprise plans offer governance, collaboration, and API-level flexibility for building internal copilots or deploying AI across departments.
- Voice & Multimodal Experiences: If your focus is expressive real-time interactions, GPT‑4o remains unmatched—especially for chatbots, voice assistants, or learning apps that require fast, humanlike conversation.
Final Thoughts: One AI Family, Many Strengths
GPT‑5 isn’t just a faster model—it’s a robust, safety-first system that merges reasoning, creativity, and real-world utility. It democratizes access to expert-level intelligence while raising the bar on accuracy, honesty, and multimodal comprehension.
While GPT‑4o continues to lead in voice and real-time interaction, and o3 holds legacy value for developers, GPT‑5 now anchors OpenAI’s entire ecosystem.
Whether you’re building AI copilots, intelligent workflows, or custom applications, partnering with an OpenAI development company can help you leverage the right model for your goals—faster and more effectively.
No matter your role—developer, founder, or enterprise strategist—GPT‑5 is likely already powering the tools you use in 2025. Now’s the time to build with it.
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