which emulator is for what in retroarch
RetroArch is a multi-system emulator for Linux, Windows, Mac OS X and *BSD. It is formerly known as SSNES. Its design and background is quite different than most other emulators as RetroArch does not implement an emulation core itself. RetroArch talks to libretro, a generic emulator core API. This means that RetroArch is core agnostic, and it does not care which emulator core is running. Currently there are libretro implementations for systems such as SNES, NES, GBA, GB/GBC, Genesis, and even arcade games (Final Burn Alpha). libretro isn't only usable for emulators.