My situation: just baught a Stradalli T-7 frame and am currently buying componets. I've hit a wall with the BB. im working with a BB86 frame, I have done a lot of research and think I have a BB86 megaexo press fit BB in the bike now. am trying to figure out what crank arms to buy (buying used) and discriptions amount to I.e. Fits GXP....fits megaexo....
The problem I see is that there seems to be a few different types of megaexo BB and it seems GXP is describing the spindle instead of the BB it fits into. I understand BB30 and BB86/90 BB90/95 but I don't understand GXP and megaexo BBs.

Can someone explain megaexo and GXP to me (please! I'm not being lazy, I literally can't find jack s*** about them and it seems everyone uses this to determine what crankset they have)

Thanks to all that reply!