What's the difference? I thought the vision ai component of gemini 3 is called nano banana?

That’s about generating images, the other side is about understanding images.

i assumed nano banana was just a tool that gemini 3 used though i don't know

Gemini 3 Pro's text encoder powers Nano Banana Pro, but it has its own image decoding model that decodes the generated image tokens into an actual image, which appears to be the more pertinent issue in this case.