Escorts officially are classed as the same as a companion, a protector etc that sort of thing. Unofficially though we all commonly class escorts as prostitutes.
You got prostitutes who sell just sex and nothing else.
Then there's escorts who do basically anything for money if they are ok with doing that-anything.
Basically, its legal to advertise sex for money like on the internet and only if money is exchanged in an indoor location, so if you meet outside in a car and money is exchanged followed by sex then that is illegal, likewise for any outside activity. Its a very grey area, examples:
If the guy casually meets a girl in a bar and she say's "sex for money" then that is illegal.
Same situation but if the guy asks her what she does for a living and she responds with escorting followed by the guy asking "how much money for sex?" then that is illegal. However if he asks her how much money for her time, she responds with a price, discuss what things you both enjoy and where to go his or her place - then that is legal.
A stripper in a gentlemans club during a private dance; if she tells him (or verbally instigates) she could offer sex for money then that is illegal even if no touching has commenced. However, if they talk like:
him: any extra's? her: yes sex for money - legal because she didnt approach the subject to him, and legal for him as he could be implying anything not just a sexual act. See how its a grey area? It would then only become illegal if they have sex in the club or outside, so they would have to go back to his or her place for it to all be legal.
Police dont bother with tracking down said possible examples though, they do if they get wind of things like trafficking, under age, pimping, or things like if a prostitute on the street is being a pest to the local residents.
The police arnt bothered by the fact if an escort is being a prostitute, what they are bothered about is if she is paying her taxes or not.