Does standalone emulators are related to RetroArch?

Hello there,

just bought GameShell and still new to all these emulators, bioses, cores and etc. Tried searching over the forums, but did not find answer to my question. Does RetroArch is related to the build in emulators which comes preinstalled on the system? I mean if I change some settings in RetroArch does this affect the build in emulators? Another one is: why do we have both build in/retroarch emulators, my understanding is they do the same job? (or probably the build in have better performance) And last: what should be preferred? RetroArch or the build in emulators?

standalone emulators are not related to RetroArch