[bdc]

In Windows, 'X' "makes no sense", while in OS X, 'X' is "clear." Okay, got it :).

[Samuel_Michon]

In isolation, you could say Windows and OS X both use an X on a red background (on mouseover). However, we're not talking about just one button and one hover state, it's part of a set of three (plus hover states).

'Cat, Dog, Rabbit' makes sense, 'Cat, Sonic boom, Carpentry' does not.