Nemotron vs. StableVicuna

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

StableVicuna is an RLHF finetune of Vicuna using datasets such as the OpenAssistant Conversations Dataset and the GPT4All Prompt Generations dataset.

Initial release: 2023-04-28

Reference

https://huggingface.co/CarperAI/stable-vicuna-13b-delta

Further Reading

• https://stability.ai/blog/stablevicuna-open-source-rlhf-chatbot