Wrong forum, but actives use a battery and have more gain and passive are just... passive.
It all makes sense
We're capable of beauty
Through sounds that make on cringe
The dogs only hear us now

Actives use batteries. Passives do not.
Quote by Noyon999

They will be on their knees begging for mercy... But The Pit shall have no such mercy and finish them with a "HADOKEN!"

Founder of the Help UG Achieve World Domination group and Vice President of UGtopia
One is very active, jumps around and screams etc, the other one is passive and it just sits there not doing anything.
actives generally have a higher output (the pickup itself doesn't, but there is a preamp inside [don't quote me on that]) and require a battery. Usually used for metal.
Passives do better on cleans and don't need batteries.

It's all preference.