Just wondering what is the difference between Eclipse JUNO, and ADT from Android developers site. Which is better to use on Ubuntu 12.04?
To develop android application you should use Eclipse and ADT. Eclipse is a development environment for multiple programming languages. For example, with the Java Development Tools (JDT) it support Java development. ADT (Android Development Tools) is an another extension of Eclipse to support Android development. It adds a lot of functionality to Eclipse e.g. debuging tools which help you while coding and running android applications. However, to run Eclipse with ADT you still need the Android SDK.
The android developers site is always a good start to develop android applications. You will find there everything you need.