5150VS5150II
5150/6505
VS
5150II/6505+
The 5150II/6505+ has the following differences:
Rhythm channel crunch is foot switchable
Adjustable bias (cold range)
Separate EQ for each channel
Separate presence and resonance for each channel
Brighter overall tone
Better clean tone
A little less gain on the lead channel (6 gain stages)
A lot less gain on the rhythm channel (3 gain stages)