[okdonk]

I myself until now don't know the differences. But i think it's just for user preferences of using whst kind of ammo in the mags. Like penetrstor ammo, tracer ammo and etc.
But for sure Magpul followers are the best out there. They can be used in some steel/ aluminium mags.

 

[okdonk]

Donk- when the mag is loaded, you can't see the follower.

You are right!, i didn't think about that. Haha my bad