VTi is VTEC(variable valve timing and lift electronic control) technology and Altis is VVT-i (variable valve timing-intellegence).
VTEC is tuned on each engine to kick in at the point where the engine's torque curve starts to falter, and then picks it right back up with better breathing.
VVT-I is a gear based system that move the cam shafts, generally causing the same idea, alter the cams to keep the engine producing more power than a static shaft. It continuously work throughout the RPM band to produce maximum output.
As far as technology is concerned, both are variable valve timing.