They are 2 names for the same thing. Companies just stopped calling them laptops since there have been cases of them overheating from people setting them on their laps and blocking air flow.
A notebook generally has less features than a laptop such as: being lighter, having no CD/DVD drive, a smaller screen, and a lower-end graphics card. Notebooks tend to have longer battery life...
Laptop and notebook are the same, just different terms for it. Netbook is one of the mini-laptops, with less memory etc, mostly just used for accessing the internet
A notebook is a sort of lesser laptop. A tablet is an entirely different medium, known for being flat and having no physical keyboard. A laptop is a portable, usually folding computer.