The Wizard of Oz wrote:
Actually, USB has about as much in common with RS-232 as a giraffe has with a grapefruit.Bad analogy. A better one would be like what a bison has to do with acow. The hardware protocols can't be a lot different.
Good analogy. Both USB and RS-232 are serial protocols. Both giraffe and grapefruit start with a "g". But that's where the similarity ends.
I won't go into details. There is plenty of info on both USB and RS-232 on the net.