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GPT-4o vs GPT-4.5: Complete Overview. Launch timeline, Modalities and UX, Reasoning and benchmarks, Latency and cost, Safety and alignment, Use cases

The twelve months separating OpenAI’s May 2024 announcement of GPT-4o and the February 2025 preview of GPT-4.5 saw two very different philosophies of progress.
GPT-4o (“o” for omni) pushes the frontier of how we interact with an AI—merging speech, vision and text into one low-latency experience. GPT-4.5, code-named Orion, pushes the frontier of what an AI can understand—scaling unsupervised learning to raise factual accuracy, emotional intelligence and creative nuance.

Here we go through every major difference so you can decide which model best fits a given job.

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1  Launch timeline and design goals

  • GPT-4o — released 13 May 2024; goal: deliver real-time, native multimodal interaction that feels conversational and affordable.

  • GPT-4.5 — released 27 Feb 2025 as a research preview; goal: scale dataset, parameters and post-training so the model “just knows more” and hallucinates less, even if that means higher compute cost.


2  Modalities and user experience

Aspect

GPT-4o

GPT-4.5

Inputs

Text, still images, audio and short video snippets (via frame sampling)

Text and images (file or camera); no speech or video yet

Outputs

Text, images and streamed speech (average 320 ms response)

Text (and DALL·E-generated images when invoked); no native voice

Interaction feel

Instant, human-like back-and-forth; can understand tone, background noise and multiple speakers

Classic chat cadence; deeper elaboration, warmer tone, richer context retention


3  Reasoning and benchmark performance

  • GPT-4.5 registers double-digit gains over GPT-4o on graduate-level science (GPQA), advanced mathematics (AIME ’24) and multilingual knowledge (MMMLU).

  • GPT-4o still delivers state-of-the-art vision and audio understanding, fields that GPT-4.5 has not yet entered.

  • Both models share a 128 K-token context window, but GPT-4.5 is more consistent at long-context recall and summary.


4  Latency, efficiency and cost

  • Latency: GPT-4o’s single-network architecture means sub-second speech replies; GPT-4.5 responds at ordinary chat speeds because every request traverses a larger model.

  • Price: GPT-4o is roughly half the token price of GPT-4 Turbo and available in the ChatGPT free tier; GPT-4.5 is restricted to ChatGPT Pro (with planned Plus rollout) and carries a premium in the API.

  • Throughput: developers get higher rate limits with GPT-4o, making it the economical choice for high-volume applications.


5  Safety and alignment

Both models inherit RLHF and system-card evaluation pipelines from GPT-4 Turbo, yet diverge in emphasis:

  • GPT-4o introduced audio-specific guardrails (e.g., limited voice presets and red-team audits for impersonation risks).

  • GPT-4.5 added new large-scale supervision techniques that improve instruction-following and reduce hallucinations in factual queries.


6  Ideal use cases

Choose GPT-4o when you need real-time voice translation, multimodal customer support, accessibility tools that combine sight and sound, on-device conversational agents or any product where response time and cost dominate.


Choose GPT-4.5 when you need long-form writing assistance, nuanced coaching, design ideation, complex multi-step coding, enterprise research copilots or analytical dashboards that demand the highest textual accuracy.


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