You assume correctly.

In the case of the above, the following command would generate that output:

git difftool f7c2fe7ca6f58576fcf0b586ebee4edaea580259..659bd91052ffd3bdc223eabfcff775eb51ed3c8f -- vim-custom-steem-syntax.steem

At the time that I was editing the file, the most recent change was most likely f7c2fe7ca6f58576fcf0b586ebee4edaea580259 and so I could have pulled up the comparison with just one hash as the target, 6ac42fb08e211c220125bc77b84bf6b259f8efec, in which case it would look like this:

git difftool 6ac42fb08e211c220125bc77b84bf6b259f8efec -- vim-custom-steem-syntax.steem

But that's a lot of typing, so I probably only did the first few characters of the hash and let it prompt me for each file to view, or:

git difftool 6ac42f

This works because my diff tool of choice is set to vimdiff. Otherwise you'd have to type the slightly longer:

git difftool --tool=vimdiff 6ac42f

Or, if you like guis:

git difftool --tool=gvimdiff 6ac42f

Note that I couldn't just do git difftool because the changes were committed on save, so I had to pass some hash in to get diff output, otherwise there wouldn't be a difference as the content would already be committed.

Now, if you are wondering why it looks like the commit message is in the diff, that's actually because the article text contained a quote of a previous commit message, that's not the revision history of the current diff, but rather the file content being diffed.