Netbook - a very small laptop designed for the internet and nothing else, they often run email and browsers and not much in addition to that. Some take office, but some don't even run windows.
Notebook - just a common name for what you probably know as a 'laptop' - 14 to 17ish inch screens, few gigs RAM and often better graphics and CPUs, designed to be a 'desktop' computer that you can carry around.