They aren't the same thing and the article here specifically uses the term decriminalized.
Is there honestly a profound difference between the two? If prostitution were legal, yet regulated, failure to adhere to the proper regulations could still result in the same consequences for the cases that criminal policing targets anyway. Does legalization mean permissible with documentation?
What are the specific results of "decriminalization"? Does it simply mean that it's classified as a lesser misdemeanor, punishable by fines and community service, rather than felonies plea bargained to trespassing, that result in years in county lockup after repeat offenses? Or does it mean ordinance violations for things like disordely conduct, that do not accumulate as serious offenses on an individual's arrest record?
Does decriminalization mean that certain parts of town don't get policed as much on the weekends, and cops look the other way, when it comes to certain hotels and drinking establishments?
Does regulated legalization mean solicitation goes unreproached even in broad daylight on a sunday morning on main street, so long as you carry your laminated photo ID card on your person, while you loiter near the gas station?
Does legalization mean that johns experience zero repercussions for patronizing regulated whores, while decriminalization leaves johns open to petty offenses where they still cannot patronize under any circumstances, but if caught no jail time will result?
Let me see if this helps make it clear:
I used to subscribe to some sort of energy/environmental magazine. Solar power or whatever. And there was a story about a guy in Chicago who wanted to make his own home-grown power and go off the grid in the midst of Chicago. And he called around to see what agency was in charge of this, who he needed to apply to for permits and that sort of thing. And he got told, basically, that this had not yet made anyone's radar and there was no agency in charge of this stuff. There was no where he needed to go in order to get permission.
He hung up the phone and realized as long as he didn't mess up badly and make the radar of the police or others, he could do any damn thing he wanted. So he set about doing what he wanted and went off-grid. It was perfectly "legal" to do so and no one was up in his business about it. It was a new thing and no rules had yet been made for it, basically. So there was nothing stopping him.
Legalizing prostitution would be more akin to, say, the way we have driver's licenses. There would be a process for applying to get your hooker's license and proving you did not have VD or whatever. Decriminalization is more just saying "If a woman (or other person) wants to charge money for sexual services, she is not breaking the law and cannot be charged with a crime for that."
Or so I understand, law not being some strong point of mine.