As far as I know there is NO difference except in the carrying case and sometimes the colors. they are very accurate and a joy to shoot especially with a Knight suppressor
Bob
I can say from experience that the USP is great gun. I've had a full size .40 S&W for 8 years and have never had an issue with it. Several friends have purchased them after shooting mine. Even one guy who vowed never to take the HK plunge, you know who you are (OneBadV8). Another friend has a USP Tactical .45 that I've carried and shot and it too is a fine weapon.
Hopefully this helps.
Who? What?