Differences that I've noticed:
1. Lichess rating is ~200-300 points ahead of a Chess.com rating. Not in the sense that players are better, but an 800 player on Chess.com will probably be 1000-1100 on Lichess.
2. Fantastic analysis tool. Chess.com analysis tends to be a bit funky sometimes.
3. Zen Mode. Not really a pro / con, but it's nice to hide the UI and just have a board on the screen when playing.
4. Free, obviously. No ads.
5. Younger audiences may want to play where their favorite streamer plays, which tends to be Chess.com for nearly everyone unless you're Eric Rosen. Hikaru Nakamura, GothamChess, Magnus Carlsen, Botez Sisters, Anna Cramling, and Chessbrah are all on Chess.com.
6. Chess.com has better puzzles, although limited on the free tier.
I don't have exact numbers on population for both platforms, but if someone can correct me, I'm fairly sure Chess.com holds the majority of players.
Edit: Spelling
1. Lichess rating is ~200-300 points ahead of a Chess.com rating. Not in the sense that players are better, but an 800 player on Chess.com will probably be 1000-1100 on Lichess.
2. Fantastic analysis tool. Chess.com analysis tends to be a bit funky sometimes.
3. Zen Mode. Not really a pro / con, but it's nice to hide the UI and just have a board on the screen when playing.
4. Free, obviously. No ads.
5. Younger audiences may want to play where their favorite streamer plays, which tends to be Chess.com for nearly everyone unless you're Eric Rosen. Hikaru Nakamura, GothamChess, Magnus Carlsen, Botez Sisters, Anna Cramling, and Chessbrah are all on Chess.com.
6. Chess.com has better puzzles, although limited on the free tier.
I don't have exact numbers on population for both platforms, but if someone can correct me, I'm fairly sure Chess.com holds the majority of players.
Edit: Spelling