Seriously, a 2 second Google search would give you the answer that you need. I guess it was faster to take the 10 minutes, register here, make a thread, and then bump that thread a minute latter for no apparent reason.
There are too may differences between the two that you should really look this up yourself. I promise, Google won't bite. The overall difference is that the iPad is a touch screen based device running low power hardware and an operating system built around touch input. Notebooks are essentially portable desktops as they run full fledged operating systems such as Windows, Mac OS X, etc. An iPad cannot live without a computer as it is more of a companion device, it is not going to completely replace a notebook but can do so with everyday web surfing and some tasks. It is still going to rely on a computer when it comes to syncing content.
The biggest difference between a lap top and iPad seems to be the size difference.
It's true that laptops can be found in smaller sizes, but you have to flip it open and close and it ends up taking more space than you suspected.
The iPad is slim and fast. There are different purposes for both devices. Some people would prefer one over the other.
I (a student) would rather prefer a Net book laptop because I need to be typing fast and the keyboard allows me to do that.
The iPad is a wonderful media/content consumption device. I love mine for watching video, reading digital comics and magazines (love Zinio), browsing the web and checking e-mail. It's also okay for brief e-mail replies, but I hate typing more than a couple of sentences without real keys. I use the Apple bluetooth keyboard when I expect to write lengthy e-mails.
The iPad is not a good content production tool. If you want to write long documents, create big spreadsheets and produce extensive presentations, or if you plan to do photo, video or audio editing, you need a laptop instead.