Movie Soundtrack VS Movie Score

[Helkite]

I'm just wondering, what is the difference between a Movie Score and a Movie Soundtrack? I've always thought that a Soundtrack contained songs played in the credits (or sometimes during an interlude during the movie), and those songs are usually lyrical. A score contains (usually) symphonic background music played during the entire movie, usually non-lyrical.

That's what I thought.

However, many movie music CDs I bought seem to contradict my reasoning, for example, on the case of the FOTR "movie music", it said "Original Motion Picture Soundtrack"...

Can anybody clear this up for me? Thanks...