GIT - How to find commits made specific to a branch?

I want to find commits made specifically to the branch 'rel-7.4-r16'. Here is the command

Simple

git log  refs/remotes/origin/rel-7.4-r16 --not $(git for-each-ref --format='%(refname)' refs/remotes/origin|grep -v refs/remotes/origin/rel-7.4-r16)

with log pretty format

git  --date=iso --pretty=format:'%h %ad %an %s' 
 refs/remotes/origin/rel-7.4-r16 --not $(git for-each-ref --format='%(refname)' refs/remotes/origin|grep -v refs/remotes/origin/rel-7.4-r16)