In general, I also had the feeling that the lichess UI is a bit more immediate, it was easier for me to get around.
But I think a big difference is not in features or UX, but the behaviour of the players. Because of its free nature, lichess has several problems that I haven't seen on chess.com. I do use chess.com significantly less, but I've always had civil interactions there.
On lichess:
* people are free to act like jerks, since they will likely get away with it. My chat's turned off, but I can't do anything about people abandoning games when they lose, trying to pretend that they've left so that I don't pay attention and lose on time, etc.
* severe lack of gentlemanly behaviour. As an example, I don't think I've ever seen someone concede a game, it's almost always a bitter fight way past the point a reasonable player may accept defeat.
* Now that I think about it, lichess brings the worst in me. I want to crush my opponents and taunt them. Yet another reason why my chat's turned off.
Blitz is a vicious game, full of trickery. :)