Essentially there is no difference and the terms are frequently used interchangeably. As a rule of thumb, notebooks/netbooks tend to be much lighter and more portable. This is achieved by cutting the hardware down to the bone, so it's likely that a notebook won't have CD/DVD drives built in and will have a minimal number of ports. The memory and graphics will usually be at the lower end of performance. A laptop is the opposite of this, a larger bulkier machine, built as a portable alternative to a desktop PC. Netbooks/Notebooks are ideal for those who need to access their computer when on the move and are cheaper and lighter. Laptops are more often used by people who want a computer around the home, but don't want the large footprint of a desktop PC.