Nemotron vs. Pythia

Overview

Nemotron is NVIDIA's open model family for efficient reasoning, coding, long-context analysis, and agent orchestration. Nemotron 3 Ultra is the current flagship.

NVIDIA introduced the Nemotron 3 family in December 2025 with Nano, Super, and Ultra tiers. Nemotron 3 Ultra, released in June 2026, is a 550B-parameter hybrid Mamba-Transformer mixture-of-experts model with 55B active parameters and a one-million-token context window. It is optimized for long-running agent workflows, tool use, code, multilingual reasoning, and high-stakes retrieval. NVIDIA publishes the weights, training data, recipes, and fine-tuning workflows under the OpenMDW-1.1 license.

Initial release: 2025-12-15

Current generation: Nemotron 3 Ultra

Reference

https://build.nvidia.com/nvidia/nemotron-3-ultra-550b-a55b/modelcard

Further Reading

• https://research.nvidia.com/labs/nemotron/Nemotron-3/
• https://developer.nvidia.com/blog/nvidia-nemotron-3-ultra-powers-faster-more-efficient-reasoning-for-long-running-agents/
• https://build.nvidia.com/nvidia/nemotron-3-ultra-550b-a55b/modelcard

Overview

The most recent (as of May 2023) effort from EleutherAI, Pythia is a set of LLMs trained on The Pile. While it appears to outperform OPT and GPTNeo, its performance against GPT-J is unclear. Versions of Pythia have also been instruct-tuned by the team at Together.

Initial release: 2023-02-13

Reference

https://github.com/EleutherAI/pythia

Further Reading