Prostitution consist in giving your body to anyone, in exchange for money. Which is basically what normal women do anyway, you have sex after paying them nice lunches, gifts, whatever. A whore is the incarnation of honesty and generosity. There is no bullshit, she tell you her price, and you buy it. A whore doesn't discriminate, she open her legs to anyone who can pay. Moreover, it's common knoweldge for anyone who knows them, that they often give reductions to their poor clients. It's not a surprise that many catholic writers saw in the figure of the prostitute something mystical, a perversion of the figure of the Saint, neithertheless marked by charity. A saint give her soul, a whore give her body. But they are both defined by the offering of themselves, and the whore is closer to the saint that the "honest married bourgeois women", who is defined by her hypocrisy, because she doesn't admit to sell herself. Only dumb puritans don't understand this, because puritanism is the hate of visible dirt, which allows real evil to prosper. But the world is full of dirt and when you don't want to see it, you become even dirtier. A whore take the dirt on herself, and in that way she's more beautiful and heroic than a women who pretend to be respectable when in reality she also sell herself for money, only with high criters of selection.
Let me try to clarify, of course a prostitute doesn't go in the business with an ideal of sanctity or morality. She goes there because she wants money, and money is what give you security, the possibility of having various hobbies and pleasures. In the same way the honnest women marry someone because his situation allow her to have a certain economic condition that will allow her to live like she wants, a whore sell her body to acquire that situation. At that point, no difference, except that the whore give herself to anyone.