[zeromotorsports]

VTEC engages a rocker arm extension and makes a small cam act like a large cam which is the sudden engeagement. i-VTEC does the same only it adds VTC (Variable Timing Control) which advances or retards the intake cams timing.

VVT-i is basically like hondas VTC...it is constantly adjusting the intake cams timing. VVTL-i is the same thing as i-VTEC, it adjusts the intake cam timing and the has "lift" whwhich makes the small cam act like a big cam at a certain engagement point