I have a Gen 3 G34, Gen 4 G19 and Gen 4 G32.
I believe he was making reference to legalities of resale and the ability to own/transfer from LE to civilian, and referring to mag capacity.I have a Gen 3 G34, Gen 4 G19 and Gen 4 G32.
The Gen 4 grip has a more aggressive texture and the back strap can be changed. The recoil spring is completely redesigned. There are a few miscellaneous interior parts that are also different.