I'm no expert but here is what I've picked up over the years. The white crappie don't seem to like clear water as much as blacks. I think with Ky lake clearing up, it is driving the whites deeper. I know that when we get the big rains and lots of run off, the whites seem to pull back up in the shallows and aren't as spooky. As far as technique for catching each, the black crappie seem to like a moving target more. I vertical jig with two poles. When I fish a bed, I move in real slow and do a twitching presentation with the jig. This is where I pick up the white crappie. Then I will sweep the front of the boat from side to side over the bed which makes the jig dart up and to the side like a baitfish that is spooked or excited and this really seems to excite the blacks. Trolling is also a great way to pick up blacks but there are no hard and fast rules to catching these fish. I catch both species using both methods. I agree that the blacks do move in shallow early and stay longer. I caught blacks this summer in July in three feet of water. Had to hit them early but they were there.