In the EC 575 variety, the bronze hook will deform with pressure (a plus for pulling out of snags) where as the gold one tends not to bend and will ultimately break under pressure... I'm not sure if the temper has to do with the application of finish or if the finish is simply indicative of the temper. In the bass jig selections, black nickel hooks are much the same as gold, having a temper that allows less bending (and ultimately breaks) whereas the bronze hooks will deform as with the thinner wire version(s).
Other than mold specific hooks, like the 28o for the poison tail, I generally gravitate towards the bronze hooks simply because of the nasty cover I fish.