whats the differance in the to can one do any thang the other can't?

 

The VAFC II has a greater resolution I believe. You can adjust fuel in 200 rpm increments where as the VAFC I is adjustable in 500 rpm increments. Also, the VAFC II allows you to have two different settings saved. There's probably more, but that's all I know of (and that might be inaccurate info), I don't own either of them.