How in git under windows compare 2 versions of a file in one branch?

just compare two versions of the file

git diff <sha1_1> <sha1_2> -- filename 

two minuses suggest to the gita that what’s next is the file name, not the parameters. ha1_1 and sha1_2 are the hashes of commits to compare. You can also write the names of branches / tags.

if you need to open it in a third-party utility, then another difftool command is used. But she needs to specify the "tool".

 git difftool -t winmerge <sha1_1> <sha1_2> -- filename 

it is quite possible that he will not find it. Then you need to winmerge register in the search path. Or configure gitconfig correctly .