Owlet dream sock vs smart sock

Owlet sock. What's the difference between the current dream sock and the previous version- the smart sock (specifically, the smart sock 3) besides that the new one was actually FDA approved? I'm asking about functionality of it. My son is 3 and we used the smart sock with him. Since we still had it, we've been using it with baby girl since birth (11/25 baby). Haven't had any issues but I can't help but wonder if I need to/should have upgraded to the dream sock? The smart sock seems to work fine and give us peace of mind but idk if it's missing anything as far as tracking goes throughout the night.