Do the original AeroPress and the AeroPress Go fit on the same size mugs, or does one fit on a larger size mug than the other?

The original AeroPress and the Go have the same cylinder diameter but the flange that supports the AeroPress on your cup is smaller on the Go. The Go can sit on a cup with a maximum inside diameter of about 3.25” whereas the original AeroPress can sit on a cup with a maximum inside diameter as big as about 3.75”. The original AeroPress and the AeroPress Go will both press into a mug with a minimum opening diameter of 2.75”.