I'd base it on who's playing where. A 433 has 3 central strikers that are strikers. It doesn't have the likes of Kevin Kilbane playing as wide strikers. If players like Kilbane, Garcia, and Hunt are playing wide it's a 451.
It's a bit like the way they've started calling a 532 a 352 to make it sound more attacking, only in that case it's a much worse description because of how differently the two systems work.
From memory our 460s were really 451s or 442s that we renamed on account of them not actually having a striker on the pitch.
