RetroArch is a graphical frontend for emulators, game engines, and media players.
RetroArch vs EmulationStation opinions
You need retroarch for emulationstation... they work together not alternates
RetroArch allows you to emulate directly using "cores" included with the program and downloadable from their website. EmulationStation does not do emulation, and only acts as a front-end for other emulators installed on the system.
RetroArch is core (emulator) but emulationStation is like a interface or GUI.
Happy Chick emulates more than 18 systems all in one APP, some of the included emulators are FAB/MAME/MAMEPLUS,PS,PSP,FC(NES),SFC(SNES),GBA,GBC,MD,NDS,DC,NGP,WS(WSC),PCE, ONS…etc. More games will be updated in the future...