What's the difference between Dual Core and Core 2 Duo?   

I dont know the difference...but Core 2 Duo is powerful :)
they added more things on this processor

As of my knowledge there is no difference between these two process, it just naming conversion.

In the simplest of terms, Dual Core was the 1st generation multi-core processors. What Intel did was simply fuse together two Pentium 4 chips to make Dual Core. Core 2 Duo succeeded Dual Core, and no longer boasts of the P4 technology, but instead has more energy efficient chips with lower voltage requirements and lower thermal heat threshold, making it faster and more efficient.

As one of the members said,the main difference between the core duo and dual core processors is the end of p4 technology in core 2 duo processor.The best processor is core 2 duo as it is more efficient and faster and best of the consumable memories of all the processors today

the difference of the 2 cpu is.

dual core:
this is the 1st series of core technology so there will be a pros cons in this matter but the good side of it is dual core opens the new door for core processors such as quad and multi. dual core has 2 layer of chips build in to the main cpu. but the technology of processing smooth and detailed without extending the core to its limit are not present to this one.

core 2 duo:
for me core 2 duo is the advance version of dual core. with high specs than the first one. with this cpu the core has actually has a ht technology build inside. meaning one core has and ht technoloy like the 4 processor. but in 2 core simultaneously process the given data. it smoothen the detail for maximum performance.

note:
this is actually my point of view so everything i say here are less or close to the real specs and reviews by the pros.

The answer is already given. Then too, I will give my version of answer with bit more information.... Every processor is developed based on a processor (micro)architecture. For example, Pentium 4 and celeron 4, though 2 processors, are based on same architecture i.e. Intel NetBurst Architecture. Dual core processors i.e Pentium D line of processors are based on Intel's NetBurst Architecture same as that of Pentium 4. They just took two P4 processors and fused them together to give you 2 execution cores on single processor. But then, Intel found that with these processors, performance cannot be increased either by increasing clock speed or by increasing the cores because of the heat generated by this architecture. More over, there was a serious power management problem as well. These were due to flaws in the NetBurst Architecture it-self.

So they came out with a new architecture for multi-core processors i.e. Intel Core architecture. Intel Core Architecture was developed from the older P6 architecture(that of Pentium pro, P2 and P3). They did a major re-design which allowed them to add more cores to a processor without the problem of heat. Another major difference among others to be noted was providing a combined L2 cache for both the core which further increased the performance manifold.
Hope it help you rather than confusing....

its onlt the difference in processing speed between them and it reflex is quick when compared with duo core

Ok you got the answer I have read. And I'm still lost as I don't know anyting about comp. but to turn on and get to typing. But then not a bad thing but not a good thing as well. sometimes it has cost me moneyBut have learned not to delete the main frame for what ever it was. Anyway I killed the comp. for good. So I hope you know what they are talking about I still don't my son does so I'm good. Your friend onlydia

forget about Dual core and core 2 duo! that's yesterdays technology! Real computers have Core 2 Quads and i7's(the newest generation of intel's microprocessors) under their hoods!

Okay, what everyone here is trying to explain is: Dual Core < Core 2 Duo < Core 2 Quad < i7.

the main difference is in the cache memory that they use.
the dual core processors use the single cache shared between the 2 cores, also, the size of the memory is less compared to core2duo ones.
core2duo also use 2 cores but have dedicated cache memory assigned to each of the core.