According go the Gemma 3n preview blog, Gemma 3n shares the same architecture as the upcoming version of Gemini Nano.

The ‘n’ presumably stands for Nano.

Nano is a proprietary model that ships with Android. Gemma is an open model that can be adapted and used anywhere.

Sources: https://developers.googleblog.com/en/introducing-gemma-3n/

Video in the in the blog linked in this post