These are two very different things.
Leader pricing is the practice of offering legitimate sale prices on popular items to get people to come into a store. It is typically used to get people to patronize one establishment rather than others. It is also used to get people into a store where they might also buy other items that are not on sale and have higher profit margins.
Bait pricing, by contrast, is deceptive. The store advertises a really good deal on something but is typically not really offering that deal. Instead, when a person comes in to try to take advantage of the deal, the staff uses high pressure techniques to try to get the customer to buy something that is not a good deal at all.
In this way, leader pricing is a legitimate use of low prices while bait pricing is deceptive.