Name one application that will run on a pro version and not the home, or vice versa.
You dont understand how OS version works? The newest version runs ALL software for the OS. Android 2.3 does exactly that. Of course an app written for 2.3 wont run on 1.6. Thats just common sense.
Does iOS 4.3 for ipod touch run iOS 4.3 ipad apps? No it doesnt. So how can they be the same exact OS if they cant run the same apps?
Because there will usually be an app available for both. It's not the os being different. It's screen size and resolution that there is distinction.
They are basically the same, just slightly different layout for the iPad.