Each style has its own set of instruments.
The way the harmony part is constructed in the playback styles doesn't always lend itself to all instruments.
For example the way the guitar is strummed in Gypsy Jazz would sound bad if played with a piano sounds and vice-versa the piano part in Shuffle would sound wrong if played with a guitar sound.
Guitar is not available in every style.
Here are the styles with guitar:
Jazz: Guitar Trio, Trad Jazz, Doo Doo Cats, Gypsy Jazz
Latin: Bossa Acoustic
Pop: Rock, Slow Rock, Funk, Reggae, Country, Bluegrass
Blues: all except Gospel & Slo-Mo