OpenAI is progressively complicating its LLM releases, and the recent announcement (update?) of OpenAI o3 and o4-mini shows that. But with so many models now—like GPT-4.5, o3, 4o, and o4-mini—it’s easy to wonder: What sets them apart? The GPT line is great for conversation and general tasks, but the newer O series is built for something different—deeper reasoning, sharper problem-solving, and seamless tool use. So, which one should you use? Let’s learn that through this GPT vs O series, but before, let’s summarize the o3 and o4-mini releases.
OpenAI o3 and o4-mini Release
OpenAI just released two powerful new AI models: o3 and o4-mini. The o3 model solves complex problems in coding, math, and science with impressive accuracy. It can even understand (and even reason with) blurry images, diagrams, and sketches. Unlike older AI, o3 combines tools like web searches and code execution to handle multi-step tasks smoothly.
The o4-mini is smaller but just as capable. It excels at math and STEM challenges while being fast and cost-effective. Both models show how AI is evolving—thinking more like humans, using multiple tools, and delivering smarter answers. This isn’t just an upgrade—it’s a leap toward AI that truly understands and assists.
Latest Models Overview
As of April 2025, OpenAI offers a robust lineup of models under two distinct families: the GPT series and the O series. Let’s break them down.
GPT Series
- GPT-4o-mini: A versatile, general-purpose model suitable for a wide range of tasks.
- GPT-4o: A multimodal powerhouse that processes text, images, and audio, offering real-time reasoning across data types.
- GPT-4.5: The largest and most advanced GPT model, excelling in chat and creative tasks with improved emotional intelligence and fewer errors.
O Series
- O1: Designed for complex reasoning, particularly in research, strategy, coding, math, and science.
- O1-mini: A smaller, less resource-intensive version of O1, with similar reasoning capabilities but some limitations.
- O3 (updated): The flagship O series model, boasting 20% fewer errors than O1 on tough tasks and excelling in coding, biology, and engineering.
- O3-mini: A cost-effective model that outperforms O1 in coding, offers faster responses, and includes web search capabilities.
- O4-mini (replaces o3-mini): Optimized for fast, cost-efficient reasoning, leading in non-STEM and data science tasks and topping AIME 2024 and 2025 benchmarks.
Performance: Where Each Model Shines
Performance is where the GPT and O series diverge significantly, each tailored to specific strengths.
GPT Series Performance
- Chat and Creativity: GPT-4.5 is the go-to for natural, engaging conversations and creative writing, with enhanced “emotional quotient” and reduced hallucinations.
- Multimodal Capabilities: GPT-4o can reason across text, images, and audio in real time, making it ideal for multimedia applications like analyzing visual data or generating audio responses.
- Speed: GPT-4o mini is the fastest for everyday tasks, perfect for quick responses in customer support or casual chats.
O Series Performance
The O series is a reasoning juggernaut, designed for tasks requiring deep analytical thinking. Here’s how they stack up:
- Reasoning and Problem-Solving: O3 and O4-mini lead in technical domains, with O3 setting state-of-the-art (SOTA) scores on benchmarks like Codeforces (ELO 2706 with terminal) and SWE-Bench (69.1% accuracy).
- Coding: O3-mini surpasses O1 in coding tasks, offering faster responses and cost efficiency, while O3 excels in complex programming challenges.
- Visual Tasks: O3 handles images, charts, and graphics effectively, though O3-mini lacks vision capabilities, where O1 is recommended.
- Benchmarks: O4-mini tops AIME 2024 (93.4) and 2025 (92.7), while O3 scores 82.9 on MMMU and 83.3 on GPQA Diamond PhD-Level Science.
GPT vs O Series Pricing Comparison
Cost is a critical factor for developers and businesses choosing between these models.
GPT Series Costs
- Availability: GPT-4o is available on Free, Plus, Pro, Team, and Enterprise plans, with usage limits on Free (varies by demand, 5-hour window) and Plus (up to 80 messages/3 hours). Pro offers virtually unlimited access, and Enterprise provides unlimited, high-speed usage (ChatGPT Model Selector).
- Flexibility: GPT-4o mini is a cost-effective option for lightweight applications, while GPT-4.5 is pricier but offers top-tier performance (Azure OpenAI Service).
O Series Costs
- Availability: O series models are exclusive to paid plans (Plus, Pro, Team, Enterprise), accessible via the model selector (Using O1 Models).
- Cost Efficiency: O4-mini supports higher usage limits, making it ideal for high-volume tasks, while O3-mini is praised for its cost-effectiveness, delivering strong performance at a lower price point (ChatGPT Model Selector).
When to Use What: Real-World Scenarios
Choosing the right model depends on your task. Here are some scenarios to guide you:
- Software Development: Debugging a tricky algorithm? O3’s reasoning prowess can pinpoint issues and suggest fixes, like a seasoned coder by your side.
- Content Creation: Writing a blog post or crafting social media content? GPT-4.5’s creative flair ensures engaging, polished text in record time.
- Data Analysis: Analyzing a dataset with text and images? GPT-4o’s multimodal capabilities deliver comprehensive insights, perfect for visualizing complex data.
- Math Competitions: Preparing for AIME? O4-mini’s top scores (93.4 on AIME 2024) make it a math whiz for solving advanced problems.
- Scientific Research: Tackling PhD-level science questions? O3’s 83.3 score on GPQA Diamond ensures rigorous, accurate analysis.
- Web Search Needs: Need up-to-date information? O3-mini’s web search feature provides answers with relevant links, ideal for dynamic queries.
Limitations: What to Watch For
- GPT Series:
- GPT-4o mini lacks advanced features like data analysis and file uploads compared to GPT-4o.
- Free tier access to GPT-4o is limited, switching to GPT-4o mini when quotas are exceeded.
- O Series:
- O1 and O3-mini miss out on advanced tools like memory, custom instructions, and voice.
- O3-mini doesn’t support vision tasks; use O1 for visual reasoning.
TRY these Prompts
Always best to try things. Here are some prompts you can use to test every GPT and O model to see where they stand.
The Bottom Line
The GPT and O series are like two sides of an AI coin: GPT models are your chatty, creative friends, while O models are the analytical masterminds. For everyday tasks or multimedia needs, GPT-4o or GPT-4.5 is your go-to. For coding, math, or science challenges, O3 or O4-mini will save the day. By understanding their strengths, costs, and limitations, you can pick the perfect model to supercharge your projects.
You can try models like GPT-4o, o3-mini, Claude 3.7 Sonnet, and more here.