Dvd vs LD inputs on lex mc-12b

Is anyone out there familiar with the difference between a
dvd input and an ld input. Situation: I have 2 dvd players,
1 dvd cd player and 1 dvd,sacd,dvd-a player. Both dvd1 and dvd2 inputs are in use on a lex. mc12-b next input is an ld input on the main zone. Can i use the ld input for another dvd player for testing 3 different dvd player or is there a difference between the two inputs, ie analog vs digital. The lex. also has a zone 2 and record zone which at this time are not in use. I hope this makes sense to whoever reads this. Thanks in advance.
You can use the input for anything as long as it is not an LD input that has an AC3 decoder built in.