Is THE KING OF FIGHTERS 2002 UNLIMITED MATCH a real PC game or just emulation?

It's run through emulation.

So it's emulating a a PS2 or XBOX Live Arcade? (This game was never released on NEO-GEO)

Didn't say it was, it's based off the Xbox 360/Live Arcade release with Code Mystics having incorporated other things into it.

From an interview with Jeff Vavasour years ago:

"And fans of KI might want to check out King of Fighters ’98 UMFE and King of Fighters 2002 UM on Steam, PC versions that merge the best of the Xbox 360 releases with the improvements of the later NESiCA updates."

https://www.killerinstinctcentral.com/exclusive-an-interview-with-code-mystics-jeff-vavasour/

So it's emulating the NESiCA arcade?

You asked at https://steamcommunity.com/app/222440/discussions/0/2451595019866498944/ and got a different answer, so why the continued line of questions here?

The only thing you really need to know is that it isn't a half-assed DotEmu port like the majority of the other SNK titles that are (or were) sold here (and on other storefronts).

It's called getting a 2nd opinion.

Doesn't make much sense, as you're asking a question that isn't related to an opinion and is instead rooted in fact.

2 different places, 2 different answers, point proven.