Are CPU registers and CPU cache different?

Question

Are CPU registers and CPU cache different?

Answer 1

Yes, CPU register is just a small amount of data storage, that facilitates some CPU operations.

CPU cache, it is a high speed volatile memory which is bigger in size, that helps the processor to reduce the memory operations.

Answer 2

It is not very inaccurate to think of the processor's register as the level 0 cache, smaller and faster than the other layers of cache in-between the processor and memory. The difference is only that from the point of view of the instruction set, cache access is transparent (the cache is accessed through a memory address that happens to be a cached address at the moment) whereas registers are explicitly referenced in each instruction.