With lures on GT's and Kings, I have found the kings to be far pickier as to what they want on a given day. GT's can have preferences for certain lures but I think the retrieve has more to do with it. Kingfish can drive you mad being suicidal one moment and have total lockjaw the next. Kings will swim past a live bait to eat the balloon up the line or chase lures like a bunch of kids playing games but never actually eat the thing.
Having chased both, I would say that they fight equally hard but the GT is not quite as single minded at wrapping you around a chunk of rock. I'm sure that is cold comfort for all the guys who just went to Shoalwater though!
Most of the kings I have landed off the rocks were done with a mixture of fighting techniques. Usually it is get the hookup, then back the drag right off to get it to swim as far out from the rocks as possible, then up the drag and give the fish a short stroking routine to panic it and make it burn up as much energy as possible before bringing it back in close. Once the fish comes back in close, if it is still swimming deep, I back the drag off again to send it out wide and repeat the process to tire it out some more before trying to land the fish. This worked for me when I was living on Lord Howe Island, where there is good clean water out wide of the ledge and all the evil stuff is all in close (coral and sharp volcanic rock). Going hard on them from the word go just made them angry: the harder you went the faster they busted you off. This is also in the days before Saltigas, PE line and popping rods, so maybe the approach I would use on GT's would work there too. On GT's it is more a case of put as much pressure on the fish as you physically can. They burn out pretty fast under heavy pressure so I figure the harder I go the quicker the fish comes in and the sooner it can be released. I do have the benefit of a boat though which makes a big difference with tactics, angles and so on. I think you just have to play the fish according to the lay of the land, what works in one area is not always going to work in another.
Duncan