Re: difference between?
I wouldn't mess with a throttlebody yet judgin by the mod list in your sig.
Wait for some more engine work....
If your heart is set on it though, a halfshafted throttlebody(tb) is basically a stock tb that has had the shaft holding the throttle butterfly trimmed down. It increases flow through the tb substantially over stock and is a good FREE mod. I would not buy one, you could easily do it yourself with a dremel.
The BBK variety will be brand new, I think aluminum. It will probrobly come in a bigger size, bigger than the stock 56mm. It's useless to go bigger because the actual opening after the tb is not going to be any bigger than 56mm so you won't really do anything until you get the upper intake port matched for it.
Search around here, I will too, I'm going to see if I can find the guide I used to halfshaft mine.