Possibly the best definition of nerd vs geek vs dork I've seen:
- Nerd
The "intellectual" aspect. One who uses spare time to do "homework"-esque activities. Always loves to learn.
- Geek
One with less than popular interests. Scifi, computers, or technology related things, usually.
- Dork
Refers to the social aspect. A dork is someone who is incredibly awkward socially. Usually got beat up, had his glasses broken, and received numerous wedgies in elementary school.