What I understand is that, PVOB is a special type of VOB that is used when UCM is implemented as the software configuration management process.
But my doubt is how is it different from VOB? I am new to CC but, as far as I know, even PVOB contains the same information as VOB.
Can anyone explain me?
PVob is like a vob in that it can version files and folders.
But by convention, you don't use a pvob to "add to source control".
You use a PVob as a "admin vob" for a classic Vob in order to declare component(s) in it, and to manage all the matadata associated to UCM:
In that case, as I mentioned here, PVob are visible in the ClearCase project Explorer, not the ClearCase Explorer.
As any "AdminVob", a pvob manages datatypes for the associated vobs: see "VOB datatypes and administrative VOB hierarchies".
Simply, a pvob will manage UCM types as well, making projects, streams and activities visibles for all the associated UCM vobs (which contain the actual data).
You can actually group pvob in a hierarchy, as explained in "Multiple PVOBs and a common administrative VOB".