What is the difference between Nano 328p-au and 328p-mu? Does it have to do with the updated bootloader or is it just a different board design? I want to make sure I order the correct one and I could not find a proper answer so far. Thanks.
1The only difference is the MCU package. If you're ordering the pre-assembled Nano boards, it makes no practical difference.– Dmitry GrigoryevJul 1, 2019 at 12:50
The AU and MU on the chip just refer to the shape of the chip. AU is TQFP and MU is VQFN.
You can see the full list of suffixes here (select the red "Buy Now" tab for a table).