well this weekend on our way to tahoe and he asked me a good question... whats the difference between i-vtec and regular vtec?

 

here it is, quick and easy...

vtec - variable valve timing (think about low and high lobes)

ivtec - variable valve timing plus variable camshaft timing (cams twist and either advance or retard timing in addition to vtec)

 

pretty much hit the nail on the head.