VCT and VVT are the same thing. I refer to the 5.7s "VVT" system as Variable Cam Phasing because it varies the position (phasing) of the entire (one-piece) cam in relation to the crankshaft. Since this relationship is what determines the valve timing for the engine, varying the relationship between cam and crank (variable cam phasing) results in "variable valve timing". The system on the Viper V10 is a bit more sophisticated, in that the Viper cam is actually in two pieces. The intake and exhaust events are independent of one another and are each varied independently of the other, and both varied in relation to the crankshaft. JMO, but it seems more proper to me to refer to this system as true VVT...