git reset    Commit-level    Discard commits in a private branch or throw away uncommited changes
git reset    File-level    Unstage a file
git checkout    Commit-level    Switch between branches or inspect old snapshots
git checkout    File-level    Discard changes in the working directory
git revert    Commit-level    Undo commits in a public branch
git revert    File-level    (N/A)