Welcome to the forums saranatunga,
Pentium dual core is intels way of labeling the slight differentiations from the entry level dual core CPUs and the next line up, the core 2 duo. The only difference I've noticed on the spec sheets are the Pentium Dual Cores don't support SSE4 instruction set. Unless you're using an app that uses them, you won't even know its missing.
Upendra09, that is really uncalled for. We all started with more questions than answers and the only way to learn is to ask.
Pentium dual cores are core 2 duos that didn't quite pass specs so they have disabled cache,