the diffrence between 5150 and 5102

Peavey rebranded the 5150 and 5150II as 6505 and something else. Same amp, different name.

As to between the 5150 m1 and 2, most people prefer the distortion and sound of the 5150 mk1, and I think the clean on the 5150mk2 is better, still, always best to try them all out :)