Geek and nerd are terms often used interchangeably, but ye of little knowledge do not realize the momentous difference between the two. A handy infographic/graph has come up to clarify the distinction. Creator of the graph Burr Settles used data from two twitter sources to draw inferences, plus some math magic.
To quote a part of his conclusion:
In broad strokes, it seems to me that geeky words are more about stuff (e.g., “#stuff”), while nerdy words are more about ideas (e.g., “hypothesis”). Geeks are fans, and fans collect stuff; nerds are practitioners, and practitioners play with ideas. Of course, geeks can collect ideas and nerds play with stuff, too. Plus, they aren’t two distinct personalities as much as different aspects of personality. Generally, the data seem to affirm my thinking.