MIOS is the Nintendo's system file responsible to play Gamecube game discs.
DIOS MIOS is a custom version of the system file installed in the console's system and replacing the official MIOS system file to play gamecube game backup ISO from USB.
DIOS MIOS Lite is the same, but redirects to SD Card instead of USB.
You can only have one MIOS at a time, so it's either Retail, USB or SD. You have to re-install the system file you want every time you want to change what you want to play.
In addition to redirecting file access from Disc to External devices, it has few features like cheat code, video patching or redirecting Memory card access to external device too.
DM and DML are old now and new method to play Gamecube games from external devices can be used : Devolution or Nintendont.
Both projects don't require any system file replacement or installation, and are working with both SD and USB without the need of different versions.