How can I install Plasma Active on my Android Mobile Phone and LePad(Lenovo Tablet, Android OS).
Is it a desktop for Android or a independent OS based on Android?

Plasma active is not related to android at all, it will not run on android (currently) nor is it based on Android. For practical purposes right now, you can consider Plasma Active to be totally different operating systems, like Android, the iPhone operating system, and Windows Phone 7.

It is more complicated than that technically, I can go into more details if you wish, but the technical description is much longer.

Installing it on current mobile phones is unlikely to work very well, since it is currently primarily designed for tablets. Installing it on a tablet would depend on it having hardware that is supported currently. Further, it would involve totally erasing the existing operating system and installing a new one. You will lose all existing android features and capabilities.

From the screenshot, Plasma Active is very different from Plasma Workspace.

I am not a KDE techie, but here's my layperson's view.

Plasma Workspaces is the overall name for the various Plasma offerings. Wikipedia has more (http://en.wikipedia.org/wiki/KDE_Plasma_Workspaces).

Plasma Workspaces currently consists of Plasma Desktop, Plasma Netbook and Plasma Active (for mobile devices). They have a lot in common...intentionally. But each is tailored to its respective type of device. For example, touch is essential in Plasma Active, useless in a non-touch netbook or desktop computer.

Plasma was introduced prior to the large scale appearance of netbooks and tablets. From the start, Plasma was designed to accommodate device diversity without knowing what kinds of devices would appear. Plasma Active (PA) is designed to work with a variety of OSes and hardware. It currently works well with a few operating systems (http://community.kde.org/Plasma/Active/Installation). There has been considerable effort to get PA to work with Mer (merproject.org), a project based on MeeGo.