We divide all those fancy names into few general categories, VVT (Variable Valve Timing), VVL (Variable Valve Lift), CVVT (Continuously Variable Valve Timing), CVVL (Continuously Variable Valve Lift).
Valve Timing adjusts cam timing to improve torque curve and fuel consumption for normal drivability, while Valve Lift uses different cam profile to open up the intake/exhaust valves longer to allow greater amount of air into combustion chamber, greatly increasing power and torque upon high rev.
Below is the example of categorization (some common one):
VVT – Toyota VVT
VVL – Nissan VVEL
VVT + VVL – Honda VTEC, Proton CPS, Mitsubishi MIVEC
CVVT – BMW VANOS, Daihatsu DVVT, Toyota VVT-i, Mazda S-VT, Porsche Vario Cam, Nissan CVTC
CVVT + VVL – Honda i-VTEC, Toyota VVTL-i
CVVT + CVVL – Honda A-VTEC, Toyota Valvematic, BMW Valvetronic, Porsche Vario Cam Plus
