Power mics amplify the sound of your voice - useful for boosting up a quiet rig. They will amplify everything though, so not the best choice in a loud vehicle.

Noise cancelling mics cut down background noise, making them ideal for really loud vehicles (you may have to hold the mic closer to your mouth than normal).

Dynamic mics are non-powered mics, either to replace a damaged one or as a "chunkier" alternative to the small mics with that are supplied with most new sets, or a "non-buttoned" alternative to the mics that have up and down controls.