The only difference between the two is the simple fact that Gainward guarantees the Golden will overclock to a certain speed. The non-Golden cards are not guaranteed to OC @ all.
Most people have bought regular Gainward GF3's and OC'd them to Ti500 speeds. Whether this is due to high quality yields from nVIDIA or some tweaks in Gainward's design remains to be seen.
If your box doesn't have the Gold sticker, it isn't the Golden Sample.