Different ways in which computers can be categorized?

You cancategorizethem by their hardware (Acer, Apple, Asus, DELL, etc.). Or you could categorize them by a specific harware component (CPU brand, speed, etc., GPU, hard drive type, capacity, RAM, etc.)

You can also categorize them by operating system (Windows XP, Vista, 7, 8, Mac OS Snow Leopard, Lion, Linux Ubuntu, Debian, Mint, Mint Debian, etc.).