Notebook/Laptop are the same item. But there are different types & purposes.
Small ultra-portable or large desktop replacement.
Business class or entertainment focused models.
Gaming or home office general purpose systems.
'Netbook = internet book, a small portable, low power & long battery life notebook/laptop.
Unless you get a dual core CPU the lower power CPUs and 1GB RAM don't handle multi-tasking well.
Usually with 10 or 11.6".12" screens and no DVD drive. 1024x600 or 1366x768 screen resolution are the most common screen size.
Depending on the model you may have 1GB or 2GB RAM and limited OS options.