In the imaginary world where Gmail required you to visit Outlook to view the entire thread because it hadn’t synced yet, yeah sure they’re exactly the same. In the real world the email comparison stops being useful beyond explaining how @ monikers work.
I’ll throw my -opinion- in the ring here because no one else is saying it the same way.
I did try out Firefish and enjoyed that way more as it had a fun and engaging UI and lots of extra features, but it holds the same federation and discovery issues.