How is the iPhone and iPad 2 different from a Droid device?

One of the main differences between the iPhone and iPad's and the Droid devices is the operating system.  The iphone and iPad run on a proprietary software developed by Apple and is closely guarded.  They do allow the development of Apps, but they are carefully monitored.  The Droid platform seems to be much looser in development and it is open source software which is owned by Google.  As such, there is a lot of freedom in what can be developed for this phone.