To clarify: Ubuntu for phones can run using the android kernel (which is a modified linux kernel). This means that most of the drivers should work out of the box (graphics, wireless, etc) if you use this route. You can also use a normal linux kernel but the driver support could be more problematic in that case.

The difference is that Ubuntu phone has the ubuntu userland (which includes apt) where as a normal android phone has the android userland (dalvik, etc).

The nice thing about the ubuntu userland is that it will most likely allow you to use any compiler that targets ARM. This is interesting because it allows you to make native phone application using python, ruby, haskell, lisp, etc.

Another nice thing about the ubuntu userland is that it includes the gnu programs so it will be much easier to compile and use things like openssh than it is in android.

There are two different projects. What you're talking about is the Ubuntu for Android.

iubuntu for android is just android underneath, this new announcement is a stamd alone os