As was often the case back then in the US, "soundtrack" albums were generally re-recorded for contractual reasons. The albums could be virtually identical to what was heard in the films, or radically different, or anything between the two extremes.
The A Charlie Brown Christmas LP is a re-rerecord, and there are some tracks in the film that did not make it to the LP. These include the music heard when Snoopy is decorating his doghouse, and the jazz waltz version of "O Tannenbaum."
A few years ago, someone released the music to Great Pumpkin, but it was taken directly from the film's music and effects reel. If the sessions were recorded in hi-fi, the original tapes are lost or long gone.
I have this. "The Charlie Brown Theme" on this album is heard during the Christmas play rehearsal in A Charlie Brown Christmas.
This album got a reissue in a boring cover many years later. I have the original..