Originally Posted by ctmullins
Your questions are far, far too general. Both manufacturers make many different pickups, and several different preamps.[/url]
To the OP, this is like asking about the differences between Fender and Wal basses...you've got some very different pieces of work being compared here with the fundamentals and mechanics being similar.
Different pickups sound and behave differently, simple as that. As far as preamps go, the amount of gain they add and where their EQ is centered at or how much frequency each adjusts is where the differences come in. This is basically the difference (foregoing amplifier and power section topology) in comparing one bass amp to another. Again, same basic concept but with many many more variables being present that affect the outcome.