P3449 or P3448?

I bought a version of nano B01 board, I saw the “Model : P3448” silk screen on it. Reference carrier board schematic is version p3449_b01.dsn.
What’s the difference between P3448 and P3449

Hi gzh886,

The 3448 is module, 3449 is carrier board, please refer to this topic for more details.

Do they work fine when put them together?

Yes, B01 module should work well with new version carrier board, see the “Module Documentation” section here:
https://devtalk.nvidia.com/default/topic/1048642/jetson-nano/links-to-jetson-nano-resources-amp-wiki/