Are mail-in ballots easier to manipulate than in-person ballots?

I have asked this question many times as part of other threads. I have never received a yes or no answer to the question. That is why I am asking the question on its own thread.

A voter voting in person can be identified by his/her appearance, government=issued identification and signature. If needed, the person can also be fingerprinted. I am aware that not all these checks are made. However, they can be made.

On the other hand, the only check available on a mail-in ballot is a signature match.

Mind you, the question is theoretical only. I am not alleging that the 2020 election, which saw a huge proportion of mail-in ballots, was fraudulent in any way.