The regular one can be used as just a way to give someone an egg via the command line. The 2nd one should be used if you want to automatically give players eggs with command blocks or other plugins. It takes a player UUID instead of a player so just go on google and search for the boss owners UUID. It makes it so if the boss owner changes their name it won't screw with the command. the first one doesn't have that feature and should just be used as convenience.