The Scarlet Letter - Why is the "witch" tolerated and Hester is punished? What does this say about the kinds of sins that bother us the most?

In this novel, the witch, Mistress Hibbins, is tolerated because she is the sister of a prominent politician in the colony, Governor Bellingham.  I'm not sure that we can, with total accuracy, say that her activities are tolerated much better than Hester's because the narrator does tell us that she was "executed as a witch" a few years after the bulk of this story takes place.  But it is possible that she is also tolerated for as long as she is because people are afraid of her: she does seem to have a lot of knowledge about individuals' private conversations and whereabouts as well as admitting to meeting with the Devil in the woods.  However, the fact that Hester's sins are punished so swiftly may indicate that sexual sinfulness, especially in a woman, is considered to be the most egregious type of sinfulness.