The signature basses come with a two position Q switch whereas the series basses come w/a three position (or) a continious /rotary Q (seriesII)switch,and yes there's a big diffrence in the sound the series basses are 'hollow' (chambered) which adds to the overall tone of the bass,where the other models are solid body basses, there's more meat in those series basses and of course the pups are like marky says single coil pups which is more defined in sound or more PURE sounding,,,,,,just ask your wallet!