Git stash solves a different problem, which is "I want to save these changes, and get them back". git-cof is optimized for the use-case of "I want to get rid of these changes, and I'll probably never use them again".

The most obvious difference is that commits made with git-cof never show up in git log --oneline --graph; but also they get garbage collected automatically, you don't have to manually go through "git stash list".