I spent 20 minutes sifting through the style lists on the S900 and the S910. Here is a list of styles that, at least in name, are on one keyboard but not on the other:

Pop&Rock:
S910: StandardRock, 60'sVintagePop, 60'sVintageRock, 80'sPop, 90'sRockBallad, ChartRockShfl, Unplugged, SoftRock, J-PopHit.
S900: StraightPop, RockGtrBallad, 60'sRock1, 60'sRock2, Jammin'GtrPop, Unplugged1, Unplugged2, SoftRock, J-PopHit1, J-PopHit2.
Ballad:
S910: ModernPopBld, SoulR&B, ChilloutCafe, 70'sGlamPiano, Chillout.
S900: NewR&BBallad, UnpluggedChart, Chillout1, Chillout2, PopNewAge.
Dance:
S910: Electronica, FunkyHouse, ClubBeat, RetroClub, ModChartPop, USChartHit, MellowHipHop, Ibiza2004, Ibiza2002.
S900: Ibiza1, Ibiza2, Garage, TechnoParty, DiscoChocolate, USPop.
Swing&Jazz:
S910: ModBigBandShfl, ModernBigBand, JazzGtrClub, JazzWaltzMed.
S900: MediumJazz.
R&B:
S910: ModernShuffle, Rock&Roll, KoolFunk.
S900: Rock&Roll1, Rock&Roll2, ModernR&B, ComboBoogie, BluesBallad.
Country:
S910: 70'sCountryPop.
S900: CountrySwingRk.
Latin:
S910: LatinPartyPop, Cumbia, Forro, Joropo, Parranda, Reggaeton, RumbaFlamenco.
S900: RumbaFlamenco1, RumbaFlamenco2, PopSalsa.
Ballroom:
S910 & S900 are identical.
Movie&Show:
S910: AnimationBld, BroadwayBld.
S900: Learning2-4, Learning4-4, Learning6-8, Fun3-4, Fun4-4.
Entertainer:
S910: GermanRock, SchlagerFox, EuroPopOrgan.
S900: [nothing]
World:
S910: BohemianWaltz, IrishHymn, ArabicEuro, Saeidy, Laff, WehdaSaghira, Duranguense, Bhajan, Bhangra, Xi Qing Luo Gu, Jing Ju Jie Zou, Grupera, Enka.
S900: IrishHymn1, IrishHymn2, Enka1, Enka2, PopEnka, FolkRock, LimboRock.

Beakybird

[This message has been edited by Beakybird (edited 10-30-2009).]