What is the difference between a vvti engine and efi engine?

Answer 1

VVT = variable valve timing.

It basically means that in addition to electronic control over fuel injection and spark timing, the engine also has control over the times the intake/exhaust valves open and close, which means the engine can automatically adjust itself so more power is available when you want it, but the rest of the time the engine can still be efficient.

variable valve timing enhances your engine performance, by allowing the engine to adjust the valve timing in ways that draw more fuel and air into the engine to produce more power at specific times

EFi = electronic fuel injection.

EFI is electronic fuel injection which basically means your fuel is injected electronically instead of mechanically like a carbuerator does.