Dual Core CPU Question

I'm pretty sure someone will know this...  What is the difference between the Pentium M and the Dual Core?  Compare the 2.0GHz version.  I figured that while the Pent M is a great chip, the dual core has a smaller nm and a higher bus speed.  Is there more to it?  I was reading another article about dual cores and that they run slower but work better when multithreading, etc. 

Is the Pent M 2.0GHz and one core of a Core Duo 2.0GHz the same thing (or close to it) and the benefit of the dual is having two available processors, or is there more too it?

Thanks