Pre-amps boost the signal coming from the guitar. It's also where most of tone comes from. This is the first stage the signal goes through in an amp.

Power-amps boost the signal even more, it's where all the volume comes from.

Passive means not powered and Active means powered. In other words, an active pickup takes power to work which is why they use a 9 volt battery. Passive studio monitors needs a seperate amp while Active Monitors have the amp built in.

A tube amp is a type of power amp. It just uses tubes instead of a circuit.

Kind of a basic explanation on everything, hope it helps.....