Difference between different git search commands

Question

A question from a beginner: there are several ways to search in git history. To me, it is not clear what, the difference between the commands really is:

Answer 1

git log searches in the commit messages?

Yes. Options -S/-G search for commits that change the number of occurence (i.e., add or remove) mentioned text. --grep searches through entire commit messages.

git grep seems to search everywhere: in files, blobs, trees and commit objects?

No, only in files (that is, blobs).