Musical neophytes (especially piano and strings players) regularly ask us "What is the difference between the C and Bb versions?"

1.. "[C] book" does NOT mean all the tunes are in [C].

2. Simply: C (or "concert") editions are for piano and string players. When you play a C note on the piano C key, it's a C.

3. When horn players want to play the same note from music as a C player, they need to "read" a note that is 1 step above the C book note. Don't ask me about technicalities, but it means they need music that's different from what piano and string players use, ie: "Bb book"
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Bottom line: if you play a tune in Ab, the horn cats' book has it in Bb. ("A-freakin'-flat!" you gag--Get used to it, it's a somewhat common key in Dixieland, and some classics are in Bb, Eb, and Ab!)

Now, this is potentially useful info, because if you come to play regularly with other folks, some of them will have definite key preferences for some tunes. Usually, the preferences are for easier keys--ie at banjo conventions, dozens of tunes ordinarily in Eb are played in C!!.
So: Db is in Eb, Eb to F, F to G, Ab to Bb, Bb to C. Db is rare, but the others are common.

F to G is a special case, because F is easier to play than G and many dixielanders yielded to the temptation to go for the easy.
However, many F tunes were originally in G, and G is the "standard" key among many musicians.
Bottom line: Depending on the pattern of key preferences among your colleagues, you might want to consider getting the Bb book if you don't transpose readily. Chord folk don't worry, the chord symbols in my Bb books are in the same key as the Bb sheet.

C. Couple more details on instrument keys: Bb books are used by trumpet, clarinet and tenor sax. Alto and baritone sax are Eb instruments. Trombone, tuba, and bass use the bass clef. Tubas come in all sorts of keys, but they and the bass use the C-book chord symbols, not the notes. That leaves the t-bone out in left field.
Tough darts, t-persons!  We have no plans at this time to make Eb or bass clef versions.
 
 
Revised 12/21/06