They’re not the same thing and ideally there should be clearer legislation around it all. While I would never encourage sex work as I think it’s dangerous and demeaning, those who do it ideally would register and pay tax so that it’s clear who is benefiting financially from it. However I can fully understand why governments don’t want to legitimise sex work as a career choice.
It's not that they don't want to, it's that they can't.
If sex work was indeed work like any other, the industry would have to be regulated. According to this excellent rebuttal to this claim, the following three areas are of interest:
-worker safety
-sexual harassment
-civil rights
The first would require your average prostitute to basically wear a hazmat suit (think about the extremely high prevalence of STDs present in the eyes of porn performers and prostitutes). Because what justification can there be for deciding that prostitutes do not deserve to be protected from blood borne pathogens and other potentially hazardous and infectious materials? As wingsofsteel already pointed out, applying ordinary health and safety regulations would be impossible.
Secondly, all workers have the right to be protected from all forms of sexual harassment. Applying the law to prostitution as just another job, would mean applying the rules governing a workers right to be protected from all forms of sexual harassment. This includes protection from the worker's managers (ie pimps and traffickers), colleagues and clients. The latter of course poses difficulties, because if sex is the commercial commodity, how do you separate unwanted sexual conduct from that which is wanted. And if it is - As expected - simply impossible to protect prostitutes from sexual harassment at work, are we once again, as with the health and safety regulations going to make an exception for prostitutes? One that excludes them from the legal protection all other workers enjoy? With what justification? That they agree to it? That they exempt themselves? Then what other employers are going to pressure their staff to sign wavers, declaring they are foregoing the right to expect protection from sexual harassment? Bar managers? Gym trainers? Police officers?
And lastly, the human rights aspect is always looking at the prostitutes but what about the clients? Refusing service to someone in a protected category is unlawful discrimination. So the independent prostitute who has her own rules and preferences, who for instance does not want to have a 67-year-old or a woman or a Catholic priest as a client is illegally discriminating against these people.
And what about contract law? She enters into a contract with a client but changes her mind (for whatever reason). Can the client sue her for breach of contract? What if she just suddenly could not face having one more client that day because the previous punter had hurt or disgusted or upset her too much. Can the law force her to provide a service to this client?
And what other jobs might then include a job responsibility of providing sex to clients from their employees? Or can receiving benefits mean that your job centre worker can sanction you for not accepting prostitution?
They really haven't thought this through at all. Sex work is work is nothing more than a rallying cry for those who condone, support and promote the exploitation of women and girls for the benefit of men.
Here is the link to the article
logosjournal.com/2014/watson/
It's written from a US perspective, but the same principles apply in the UK.