One significant difference is that iOS devices get security updates far longer than most Android devices.
The amount of information every app you install wants to harvest is ridiculous, on iOS they can do this unchecked, even if you'd rather they not, on Android if you're willing to do a bit of work, you can have near complete control.
Maybe not quite as much control as that feeling of hitting Ctrl+D for the first time after installing SoftICE, but... pretty damn good. :)
I myself have been using Adblock Fast for quite some time now.
With adaway on Android I'm able to block inapp ads, statistics and demographics reporting services, crash reporting services and other privacy invading services.