They're the same 30mm scale. All of the unique non pinup models are the same size as well. Some of them feel a little taller, but I think it might just be certain models like the white speaker that are supposed to be exceptional humans. Aside from the boobs they're in line with the game minis.
Re: the xmas knight, pretty sure that's one of their 54mm line (if you're not familiar, 54mm is a fairly rare but established scale that's usually for display models but occasionally used for skirmish games)
Re: the holiday speaker scale, yeah, they're apparently large, but I'll trust the 3 I've seen (regular, pinup, sword collector or w/e) consistent scale over the 1 that's off. I've seen low poses get bizarrely increased scale as a weird compensation in other systems and assume, intentional or not, this falls in that category.