That is sort of underselling it, Differential has the following features in common with CodeFlow:

- Easy to see the changes an author makes over time to a review

- Integrates with the Package and Ownership system to automatically assign reviewers

- Easy work on changes that touch many files

- Inline lint and code coverage results

- Built in display of unit test and CI results and overall coverage %

- Draft mode to delay review until tests & lint are clean

- Comments move properly as you make changes

- Easy to mark comments as done and find outstanding ones

- Comment on multiple lines instead of a single one

Things that are missing:

- No ability to comment on single characters

- Cannot mark certain files as important

- No way to explicitly mark a change as "simple" (like a rename)

- No web UI to make quick fixes (compared to GitHub is what is most missed)