nothing. they are the same thing, just one is short for the other (try and guess which, i bet you'll be pleasantly surprised!). you install it by routing the exhaust manifold to it, then it to the exhaust, as well as running oil lines, and Intake
tubing to the compressor side. there's more to it, and it's far from easy. go to www.c2power.com
and d/l the install manual. depending on boost levels, a lot to nothing will have to be upgraded. in fact, the c2 kit comes with a piggy-back ecu which will negate the need for a standalone ECU.