There is no difference. None. She is still an individual who has a Right to her own person. "Acts of capitalism between consenting adults."
Once that "consent" is removed, it's rape. Period.
For all the reasons stated previously, it shouldn't be. While she's a street vendor, she's willing to sell it.
If a hooker says "No" simply because the guy's unwilling to pay for it, and you want to call that "rape," you've defined the word "rape" to mean taking sex without paying the going rate for it.
That may be a lot of things, but it's not rape.