The Writing Room's Versions tab lists every draft with its label, note and date.
Compare produces a line-by-line diff between any two versions of the same script, showing additions and removals. Comparing versions across different scripts is refused — the diff would be meaningless.
Restore takes an older draft and appends it as a new version on top. Nothing between is deleted. The drafts you skipped past are still in the history, and the scenes and shots pinned to them still resolve.
Restoring the version that is already current is refused as a no-op rather than silently creating a duplicate.