GPT-5.2 Codex vs Phi-4 Reasoning Vision 15B
GPT-5.2 Codex (2025) and Phi-4 Reasoning Vision 15B (2026) are agentic coding models from OpenAI and Microsoft Research. GPT-5.2 Codex ships a not-yet-sourced context window, while Phi-4 Reasoning Vision 15B ships a not-yet-sourced context window. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing. The goal is to make the tradeoff clear before deeper testing.
Phi-4 Reasoning Vision 15B is safer overall; choose GPT-5.2 Codex when coding workflow support matters.
Specs
| Released | 2025-12-18 | 2026-03-12 |
| Context window | — | — |
| Parameters | — | 15B |
| Architecture | decoder only | - |
| License | Proprietary | Microsoft Research |
| Knowledge cutoff | - | - |
Pricing and availability
| GPT-5.2 Codex | Phi-4 Reasoning Vision 15B | |
|---|---|---|
| Input price | - | - |
| Output price | - | - |
| Providers | - | - |
Pricing not yet sourced for either model.
Capabilities
| GPT-5.2 Codex | Phi-4 Reasoning Vision 15B | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: GPT-5.2 Codex, reasoning mode: GPT-5.2 Codex, function calling: GPT-5.2 Codex, tool use: GPT-5.2 Codex, and code execution: GPT-5.2 Codex. Both models share multimodal input, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
Pricing coverage is uneven: GPT-5.2 Codex has no token price sourced yet and Phi-4 Reasoning Vision 15B has no token price sourced yet. Provider availability is 0 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose GPT-5.2 Codex when coding workflow support are central to the workload. Choose Phi-4 Reasoning Vision 15B when provider fit are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Is GPT-5.2 Codex or Phi-4 Reasoning Vision 15B open source?
GPT-5.2 Codex is listed under Proprietary. Phi-4 Reasoning Vision 15B is listed under Microsoft Research. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, GPT-5.2 Codex or Phi-4 Reasoning Vision 15B?
GPT-5.2 Codex has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, GPT-5.2 Codex or Phi-4 Reasoning Vision 15B?
Both GPT-5.2 Codex and Phi-4 Reasoning Vision 15B expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for reasoning mode, GPT-5.2 Codex or Phi-4 Reasoning Vision 15B?
GPT-5.2 Codex has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for function calling, GPT-5.2 Codex or Phi-4 Reasoning Vision 15B?
GPT-5.2 Codex has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
When should I pick GPT-5.2 Codex over Phi-4 Reasoning Vision 15B?
Phi-4 Reasoning Vision 15B is safer overall; choose GPT-5.2 Codex when coding workflow support matters. If your workload also depends on coding workflow support, start with GPT-5.2 Codex; if it depends on provider fit, run the same evaluation with Phi-4 Reasoning Vision 15B.
Continue comparing
Last reviewed: 2026-04-19. Data sourced from public model cards and provider documentation.