The 10mm MP 5 was the result of the FBI HRT and SWAT whem 10mm was gonna rule before the 40 took off.
I was at a training exercise with ST Louis and Springfield IL FBI SWAT at USP Marion in 2010 and although they moved into M4’s by that point they had a few and I got to toy with them.
The main difference besides caliber is a straight magazine because the longer OAL and the biggest plus is a bolt hold open/release on the left side that kicks the bolt to the rear.
As far as internal differences probably some for the higher pressures but I didn’t get into that.