1: "ESR beta r9b dvdv direct.elf"
This is the most generic non-GUI version. Compatible with most games.
2: "ESR beta r9b dvdv direct off.elf"
This is intended for some problem games, who need part of ESR turned "OFF" after init.
But it has problems with some other games (particularly multi-ELF games).
3: "ESR beta r9b mcard.elf"
This is not intended for game booting, but for accessing burned DVDs from homebrew.
4: "ESR_GUI_test2.elf" (name may vary)
The GUI version is the most generic one when it comes to game/homebrew compatibility.
But it has the drawback of requiring user interaction to proceed with a boot.
This is especially bad for those who play games with non-standard controller (eg: Guitars)