A PC (desk top) is large, meant to sit on a desk, has a separate keyboard and usually a separate monitor that may or may not have touch screen capability. Laptops and netbooks are portable but still have a keyboard that is more or less 'separate' from the monitor tho still part of a single unit. May or may not be touch screen. A tablet is basically a portable all in one computer/monitor with touch screen capability and a virtual keyboard that appears on screen for typing. Each has their pros and cons, tho PCs are starting to become somewhat archaic.