Wirelessly posted (Mozilla/5.0 (Linux; U; Android 2.3.4; en-us; SPH-D710 Build/GINGERBREAD) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1)
Probably the main difference is the Sprint Hotspot is an infrastructure connection, while wifi tether is usually an ad hoc connection.
Oh, and you have to pay Sprint extra. Snicker