What Is Difference Between Primary Memory&cache Memory?

Primary memory is a kind of Computer Data storage. It is the kind of memory that is directly accessible to the CPU. The CPU of a computer reads the instructions stored in the primary memory and then executes them.
On the other hand, a cache memory is a kind of memory that is smaller and faster. It stores copies of data from the frequently used main memory locations. It is used by the CPU of a computer such that the average time to access the memory is reduced.
Whenever a processor wants to read or write to a location in the main memory, it first checks out for a copy of that data in the cache, and if it is present there, the processor will read or write to the cache. This reduces the time spent on the main memory.