Garageband Ipad Touch Instruments Browser

I don't know if this is even easily doable.
But if so could somebody describe in general terms what functionality is missing in the cut-down version of Garageband that runs on iPhone/iPad versus the full version that runs on a Mac ?
I just got some books on Garageband (I think they're geared to the Mac version) and wanted to see if it was worth learning it for mobile sketching purposes.
And I was wondering before wasting time with the books how much of the stuff covered in them would simply not be applicable to the limited version that works on the iPhone/iPad. It might be very frustrating if I read about some function in the book only to find its been cut out of the iPhone/iPad. (I do not own a Mac). Exactly how much difference is there and how crippled is the cut-down version ?
Thanks,
Bob

Free Instruments For Garageband

Garageband ipad tutorial

Garageband Instruments Download

Tap into a wide range of instruments from around the world. And now with the Sound Library, you can choose and download more free instrument and loop packs when new sounds are released, to help you easily craft songs in your favorite styles — all right from your iPhone, iPad, or iPod touch. Download GarageBand for iOS. GarageBand turns your iPad, iPhone, and iPod touch into a collection of Touch Instruments and a full-featured recording studio — so you can make music anywhere you go. Use Multi-Touch gestures to play pianos, organs, guitars, drums, and basses. They sound and play like their counterparts, but let you do things you could never do on a real instrument.