They’re different ratings systems, and not meant to be directly comparable.

Chess.com uses Glicko with an initial rating of 1200 (https://support.chess.com/article/210-how-do-ratings-work-on...), while Lichess uses Glicko-2, and sets their initial rating to 1500 (https://lichess.org/page/rating-systems).

Just anecdotally, I’m an ~1800 rated player on chess.com, and ~2050 on Lichess. Percentile rank wise, I’m in the top 3.5% on chess.com, and closer to top 10% on Lichess.

I think this matches the general perception that Chess.com has many more casual players. This is likely a function of all the cross promotion they’ve done to grow the game, especially on Twitch. Neither site is “good” or “bad”, but my friends who play casually seem more likely to play on Chess.com.