A PC can be divided into what two main categories?

Answer 1

This is a vague question, and depends on if you are asking about hardware, or software.

In general, a computer is made up of just that- Hardware, and software.

In the hardware sense, it could be divided into the Tower/CPU*, and the Peripherals

* = The tower is often called a CPU, however this terminology is incorrect. The CPU (Central Processing Unit) is a phrase reserved for the primary computer processor, without which a computer has no function. Calling the entire computer a CPU is incorrect just as calling a car an 'engine' is not correct- Many peripherals, such as digitizer tablets, mice, and even some complex keyboards, have their own processors. Video cards also have a 'GPU', which is a Graphics Processor Unit which performs centralized processing similar to a CPU- in fact, GPUs can typically perform the same tasks as a CPU, even faster in many cases.