i think red goober is mistaken on one point,
vtec's are designed for superiour milage, having the air pulled into the cylinder on one side instead of the middle produces a swirling motion inside the cylinder to keep the fuel suspended in the air rather then splattering on the cylinder walls where it just burns.

as for difference, some but not huge, but totally right, the honda vtec engine variants are only SOHC, while the acura ones are DOHC or so i have read. in the honda variant its only the intake which is effected with the extra valve while the dohc has 2 for both exhaust and intake --- *i think* i may be mistaken on that one though.

however everything else he said, i'd have to agree with.

its suppost to have on cam profile more for economy and low end torque and the other for high end HP,, tho my friend had a 95 accord vtec automatic, and now he has a 91 stick, and the 91 feels faster.....