I believe the difference is interaction with the urine. Watersports is just peeing on people. Golden shower involves drinking it. Let me google. I will get back to you on this.
Urban Dictionary says:
http://www.urbandictionary.com/defin...=golden+shower
Golden showers seem to imply urinating into something, usually a mouth.
http://www.urbandictionary.com/defin...m=water+sports
Water sports seems to mean any involvement of urine in a sexual way, but also suggests urine enemas. D;
Watersports FAQ
Watersports FAQ: More informative than first
Okay, so, just as I suspected: Golden shower is activity/subset of the generic urine play term, watersports.