Dumplin:
what's the difference? a rape is a rape
In the Bible what counts is who is being raped. If it's the wife or fiancée of another man the rape is seen as an affront to the man (i.e. the owner of the woman) and merits the death penalty.
If it's a single woman, she is technically the property of her father who ordinarily would get a price for giving (selling) his daughter into marriage. If she were to be raped however, she would no longer be virgin and that would make her, in a manner of speaking, spoiled merchandise. (No man would pay full price for a non-virgin wife, in fact a woman who is not virgin on her wedding night was to be executed - Deuteronomy 22:13-21). Therefore the rapist has to pay the full price of a bride to her father and is stuck with her.
Like the old saying, you break it, you buy it.