Difference of cache memory and normal memory?

A cache memory is a component that stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere.

Primary memory (often referred to simply as memory) is the only one directly accessible to the CPU. The CPU continuously reads instructions stored there and executes them as required. Any data actively operated on is also stored there in uniform manner. RAM is one commonly used primary memory.