Comprehensive side-by-side LLM comparison
o3 Pro supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
NVIDIA
Llama-3.1-Nemotron-Ultra-253B-v1 is a 253-billion-parameter model from NVIDIA, derived from Meta's Llama 3.1 405B using neural architecture search (NAS) compression combined with NVIDIA's Nemotron post-training pipeline, which recovers and exceeds the base model's capability after structural compression. Released in April 2025, it supports toggling between a standard instruction mode and an extended reasoning mode via system prompt, allowing the same model to handle both rapid responses and deliberate chain-of-thought tasks. It is the flagship of the Nemotron family, available open-weight on HuggingFace and through NVIDIA NIM for enterprise inference.
OpenAI
OpenAI o3-pro, released by OpenAI in June 2025, is an extended reasoning model from the o3 family that applies more compute per response to deliver deeper, more thorough answers on complex problems. It features a 200K token context window, 100K maximum output tokens, and vision capabilities. o3-pro targets research-grade reasoning tasks, extended coding sessions, and applications where accuracy on difficult problems justifies higher inference cost and latency.
2 months newer

Llama-3.1 Nemotron Ultra 253B
NVIDIA
2025-04-07

o3 Pro
OpenAI
2025-06-10
Context window and performance specifications
Available providers and their performance metrics
Llama-3.1 Nemotron Ultra 253B
o3 Pro
OpenAI
Llama-3.1 Nemotron Ultra 253B
o3 Pro
Llama-3.1 Nemotron Ultra 253B
o3 Pro