[Mopar Guy in Delaware]

Hey Guys
The engine is just an air pump with controled explosions inside. The longer the valve is open (duration), the wider it opens (lift) the more over lap (more radical or the time both the intake and exhaust are open at the same time)- (overlap) the better charge you get in the cylinder. With a better charge in the cylingder the more force on the pistom and more power.
There's a lot of terms used that are pure marketing. No scientific basis at all.
The fellows not stuipid, he's just learning, and the term Stage this or that was and is still used by a lot of aftermarket people.
Life is a learning thing, there's always more to learn.