This particular form of birth control can work as an abortion. If it keeps sperm and egg apart, it is not an abortion. If it kills a fertilized egg that would otherwise live if it weren't for the treatment, then its an abortion. And, yes, that means that conventional birth control pills are questionable, as well.
Looking at the diagram in #1, it appears that scientists aren't quite sure how it works, or there's the possibility it might work in more than one way. There are several ways they think it might work to prevent fertilization, it appears.
Although of course using a dependable contraceptive and reduction of casual sex are both preferable, I'd think one emotional advantage of the morning after pill would be that the woman wouldn't know at that point whether she was actually pregnant or not.