A few important features of the Expert were left out by the above posts.
1. The Expert (or Elite/Tactical, with the exception of the now-discontinued USP9SD) will have the appropriate rollmark engraved on the left side of the slide.
Expert = EXPERT
Tactical = TACTICAL
Elite = ELITE
Match = No rollmark
2. The Expert (and Elite/Match) will have the complete Match Trigger parts. Older Tactical models did, too, but no longer come with all Match parts (more on
this)
3. Upgraded Recoil Spring Assembly (RSA)
4. Longer slide
5. Ambidextrous safety/control levers