What is the difference, if any, between Huck's "good" lies to protect Jim, and the King and the Duke's "bad" lies?Lying occurs frequently in this...

Huck lies in order to protect his friend and save him from slavery and from separation from his family. Huck lies to help Jim, putting himself at risk in the process. For example, in Chapter 16, Huck begins to doubt himself and almost reveals Jim to the men with guns on the skiff. He paddles over to them in the canoe with the intention of telling on Jim. However, when he gets there, the men ask him if the other man on the raft is black or white, and Huck replies, "He's white." Huck concocts an elaborate lie to protect Jim, and later feels conflicted about his choice, "S'pose you'd a done right and give Jim up, would you felt better than what you do now? No, says I, I'd feel bad- I'd just feel the same way I do now. Well then, says I, what's the use you learning to do right when its troublesome to do right and ain't no trouble to do wrong, and the wages just the same?" (Chapter 16)

The duke and the king lie in order for their own gain, and they never feel conflicted about their choices. For example, when they lie to the Wilkes girls, they do so in order to steal their money from them. They don't do it to help anyone or to act on any good impulses.