What are the differences between Dual core and Quad core processor?

These days a new Smart phone loaded with features and specifications is quite common. They compete with processor speeds, graphics, better software and what not.  We will take the case of two most growing mobile processors, Dual core and Quad Core.

Following is the comparison, so lets find out the pros and the cons of these two popular processor configurations :   

If you don't know about a Quad-core processor, click here to know more.

NOTE: Processor performance depends on the customer usage and the kind of applications run on it.