Built-In Spell Check Ignores Built-In Dictionary

Here's a thing: Apparently, Mac OSX's built-in spell checker — you know, the thing that leaves all the little red dotted lines all over the misspellings in your text files — uses a separate dictionary than Mac OSX's built-in dictionary that pops up when you hover over a word and press command-control-d.

To wit: I was typing up my latest blog post and the spell checker bitched about this:

The Spell-Checker: Fandom Not a Word?
(click for larger view)

The little red dotted line means I've typed something that isn't in the dictionary. So, being fairly certain that fandom was both a word and that I'd spelled it correctly, I hovered and pressed command-control-d and got this:

The Dictionary: Oh, But it is!
(click for larger view)

See? See that? I was right! Stupid spell-checker! What do you know?

But seriously, I find it somewhat strange that the spell-check dictionary differs from the OS dictionary. I realize that the spell-check one is customizable, whereas the OS one is not, but it seems like they should at least start off the same, doesn't it?

Or maybe it's just me.