Using Git, show all commits that are in one branch, but not the other(s)

To see a list of which commits are on one branch but not another, use git log:

git log --no-merges oldbranch ^newbranch

...that is, show commit logs for all commits on oldbranch that are not on newbranch. You can list multiple branches to include and exclude, e.g.

git log  --no-merges oldbranch1 oldbranch2 ^newbranch1 ^newbranch2

Note: on Windows ^ is an escape key, so it needs to be escaped with another ^:

git log --no-merges oldbranch ^^newbranch

You probably just want

git branch --contains branch-to-delete

This will list all branches which contain the commits from "branch-to-delete". If it reports more than just "branch-to-delete", the branch has been merged.

Your alternatives are really just rev-list syntax things. e.g. git log one-branch..another-branch shows everything that one-branch needs to have everything another-branch has.

You may also be interested in git show-branch as a way to see what's where.

To show the commits in oldbranch but not in newbranch:

git log newbranch..oldbranch

To show the diff by these commits (note there are three dots):

git diff newbranch...oldbranch

Here is the doc with a diagram illustration https://git-scm.com/book/en/v2/Git-Tools-Revision-Selection#Commit-Ranges