This is a share of a previous post on Google+ describing the difference in respective reasons that a nerd and a geek study.  It is based on article on Urban Dictionary entitled "Geek/Nerd Debate."

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Just to set the record straight, there is a substantial difference between the respective reasons that a nerd and a geek studies.

A nerd studies because studying _per se_ is fun to that nerd.

A geek studies because the geek has an obsession with making other geeks who don't study look stupid, even if the studying itself may be painful.

The nerd usually winds up studying alone for several hours at a time until falling asleep.

The geek usually winds up studying somewhere where it is possible to communicate with other geeks for 15 minutes at a time, and then writing something to show off the knowledge gained to other geeks who don't know this knowledge for the express purpose of making those other geeks look and feel stupid, even if the studying itself may be painful.

A Haskellite nerd studies Haskell because studying Haskell itself is fun to that nerd.

A Haskellite geek studies Haskell because most other geeks do not know Haskell, and the more that the geek demonstrates knowledge of Haskell to those other ignorant geeks, the more that the geek can show off that knowledge to those other geeks.

The most significant difference occurs when the nerd/geek is alone.

When a nerd is alone, the nerd keeps studying because the studying itself is fun to that nerd.  The nerd usually has no motivation to talk with other nerds _per se_ because it is the studying itself that is fun, not showing off the knowledge gained to those other nerds, who are substantially irrelevant.

When a geek is alone, the geek usually pursues an obsession, which is usually not studying, but some form of recreation, such as watching _anime_ or playing some interactive form of entertainment.  The geek is motivated to talk with other geeks because it is not the studying itself that is fun, but showing off the knowledge gained to those other geeks, who are substantially relevant:  Those geeks must be made to look and feel as stupid as possible, and it is this process _per se_ that it fun.

Incidentally, I happen to be a geek.
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