Since both are mobile os why name them differently ? Or am i missing something here ?
Ubuntu Touch is a stand-alone OS for mobile devices. It is only in beta and being tested on the Nexus 3 device. Canonical has assured fans that they have 2 major manufacturers ready to ship Ubuntu Touch with their new mobile models. It will not merge with Android or any other device, and it is simply an Ubuntu OS for mobile devices.
Ubuntu for Android
Ubuntu for Android is like a comparability mediator between the Desktop Ubuntu OS and your phone. It acts like a link between your Android quad-core phone and your computer. Ubuntu for Android will sit alongside Android, giving you the original functionality of your handset. Furthermore, 'docking' it will give you an environment where both your computer and phone act as both a phone and computer. It's a bit of a mouthful, and a little hard to grasp, but you can watch this video to learn more: