Help Vita Roms

Hey guys need some help here.

Im fairly new to the Game and cant understand the differences from the Vita roms. I use the Vita3k emu on an odin2 pro. Where are the differences in the roms pros cons and so forth. Maybe one of you can enlighten me or Point me somewhere where i can lern and understand it. Thanks in advance

Ps i Go to the Megathreat