Same thing (when it comes to so-called "hardcore" where the people are actually having sex on camera), in my opinion.
Arguing that prostitutes are treated worse so there's a moral difference doesn't fly. Some porn "stars" are treated worse than your street prostitute, and some high priced "call girls" (whether self employed or part of "legal brothels" in Nevada) are treated better than your average porn "actor."
People love porn and it makes profit, so it's not going away anymore than prostitution. Morally speaking, I must oppose both for the same reasons... it turns sex, which is supposed to be for the intimate bonding of two people for life, into a commodity to make profit (usually off of lonely individuals) and encourages people to sin. Never mind the other exploitation, drugs (you can make the same argument against professional wrestling if you want to go that route), and side negative effects like giving people distorted views of sex and relationships between women and men.
Porn isn't about values, it's about money. Making the biggest profit for the least effort. But it does have the side effect of providing all sorts of dangerous messages. A lot of young people get their "sex education" from this stuff, sadly. Part of the problem is parents don't want to educate their kids, but another part is that the pushers don't care who gets hurt so long as they get paid (like every corporate entity, one might argue).
The simulated ("soft core") stuff might be in bad taste, but it's little different than simulated violence in movies. It's art (just not everyone's cup of tea).
I've got a Christian worldview, so yeah, "of course I'd say that," people will say, but that's where I stand.
But the "distinction" between porn and prostitution is largely imaginary, I'd say. Put a peephole in a brothel and charge people admission, let them bring cameras, it's the same.