GPT-4o GPT-4.5 O1 & O1 Pro O3-mini & O3-mini High ...

Below is a snapshot of where each of OpenAI’s most talked‑about 2024‑25 models sits in the lineup, what makes it special, and when you’d reach for it.

Model	Release (date)	Core focus & stand‑out traits	Context window*	Typical use‑cases	Pricing highlights**
GPT‑4o (“omni”)	13 May 2024 OpenAI	Real‑time, fully multimodal (text + vision + audio); 320 ms avg. voice latency; 2× faster & 50 % cheaper than GPT‑4 Turbo; now powers free ChatGPT tier and API	128 k	Conversational AI with images, quick voice agents, live demos, translation	$5 / M input,$15 / M output tokens (API)
GPT‑4.5 (research preview)	27 Feb 2025 OpenAI	Largest unsupervised‑learning GPT yet; richer knowledge, higher “EQ”, lower hallucinations; no native voice yet, but supports vision	256 k (API preview)	Creative writing help, broad Q&A, agentic planning where raw knowledge matters	$30 / M input,$60 / M output
O1	Oct 2024 (public)	First “reasoning” series model – forced chain‑of‑thought before answering; slower, but strong on hard STEM & logic	128 k TECHCOMMUNITY.MICROSOFT.COM	Legal/technical doc analysis, long‑context chain‑of‑thought prompts	$12 / M in,$60 / M out
O1 Pro	19 Mar 2025 TechCrunch	Same architecture as O1 but spends more compute per answer → higher reliability on the hardest problems; premium pricing	128 k	Critical reasoning where accuracy > cost (e.g., complex proofs)	$150 / M in,$600 / M out
O3‑mini	31 Jan 2025 OpenAI	“Small but smart” reasoning model; 3 selectable effort levels (low/med/high) for speed vs brainpower; STEM‑tuned	200 k TECHCOMMUNITY.MICROSOFT.COM	Fast coding help, math tutoring, cost‑sensitive agent runs	$1 / M in,$5 / M out
O3‑mini High	Jan 2025 (variant)	Highest effort setting of O3‑mini exposed as its own picker; deeper chain‑of‑thought, still faster & cheaper than O1	200 k	Difficult Olympiad math, “explain your reasoning” tasks on a budget	Same as O3‑mini high‑effort tier
* Context‑window figures are current API limits; ChatGPT UI may differ.
** Public API list prices at time of writing.

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How the families differ

GPT‑series	O‑series (“reasoning”)
Unsupervised‑scaling lineage – bigger nets with more data → broad knowledge & style.	Deliberative alignment lineage – models are forced to think step‑by‑step before replying, yielding rigor on logic/STEM.
Faster first‑token latency; best at chit‑chat, creativity, multilingual nuance.	Slower and pricier per call, but can trace longer arguments and resist simple jailbreaks better.
GPT‑4o adds native speech, vision and image generation OpenAI.	O‑models are text‑only (O1 can “see” with external vision tool support).

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Choosing the right tool

1. You need multimodality or voice speed → GPT‑4o.
2. You need maximum raw knowledge & creativity, hallucination‑resistance, but not chained reasoning → GPT‑4.5.
3. You’re solving proofs, coding challenges, or giant PDFs where step‑by‑step logic matters → start with O3‑mini (cheap & quick).
4. Same as #3 but accuracy beats cost → O3‑mini High or O1; if the question is make‑or‑break and budget is no object, O1 Pro.

Feel free to tell me more about your workload or budget limits and I can recommend concrete prompt styles, cost calculators, or migration tips between models!