Squat and deadlift are mechanically the same exercise as far as your legs are concerned (Subject to foot position.) The only differencea are 1) your hands on DL have to clamp the weight to stop it falling to the floor (refer Max's vid for No Hand Squat) and 2) DL has shoulder joint in tension instead of (a weird form of) compression (So your shoulder line on DL is hogged instead of receiving a uniformly distributed load.)
That is why the SLDL is so important for beginners. It switches load to the Hammies and works them out like nothing else. If you stick to Squats and DLs you can choose to keep your feet in a position that is quad dominant, so you miss out on hammy goodness.