I thought I'd explain, as I see it, the difference between a geek and a nerd.
What Makes A Geek/Nerd?
Geek and nerd aren't specific computer related terms. You can be geeky or nerdy about any subject. Cars for example.. they have plenty of geeks and nerds. How do you say? Well I'll explain shortly.
For the most part geeks and nerds tend to be involved in things with a lot of detail. They both exhibit a knowledge of their subject beyond what a lay person may even think is possible. Indeed, that could be the very definition of where the boundaries lie. Good examples of this could be: role-play games, cars, computers (of course), or fitness.
A geek is someone that uses their field for productivity or pleasure, and has accumulated - through a desire to enjoy their experience more or become more proficient at a task - an extensive knowledge of a subject.
Geeks that are involved with machines (cars, computers, stereos, etc) tend to see these things as tools, and by gaining more knowledge about - and hence control over - them they intend to maximise their use of the tool. Be it driving better and for longer, or being able to code an efficient web page without looking at a reference book. The result is the same in terms of difference to a layperson. This type of geek will often know lots about the construction of their area, and can be excited by the prospect of upgrading a small part that may seem insignificant to an outsider, but it impacts (or the geek feels it impacts) the performance of their tasks.
Geeks tend to be concerned with issues in a broader scope than nerds, and are certainly more focused on issues that affect them (this journal for example - web design, and similar issues) and less with the minutiae of details.
A Nerd is someone that has taken their use of a tool or discipline and raised it so that they no longer value the result of it more than the tool or discipline itself. It is the subject that is their love. A geek might know a lot about computers, but it will be what they need to know. A nerd will learn everything they can about computers, but gain no practical benefit for this. Moreover they will experiment with things that will take a lot of time and have no real benefit to them - just because they are learning about the subject.
Nerds tend to be even more fanatical about improving in their subject than geeks, but have a more holistic approach. Rather than improving in their area they must improve overall in all areas.
Nerds are usually the more preachy and anal of the two (though this does depend to some extent on personality - a geek can be an arse too!) and are more prone to nitpicking small irrelevant details and using this as an excuse to junk the rest of the information. This is related to that Nerds are often the hardest group to teach, as their knowledge is sacred to them - and so can never be proved wrong. Sometimes even when presented with overwhelming evidence to the contrary a nerd will still claim that their knowledge is correct.
Nerds are the more annoying of the two, and the most observed. They are highly critical, and tend to put down people rather than help them (as most geeks will try to do - until they lose patience). Often the distinction is missed between these two groups, as the Nerd is usually heard the most.
Without Nerds there would be less pushing of the boundaries, but without Geeks no-one would find these things useful. Remember a geek or a nerd doesn't actually have to have a certain amount of knowledge, it is an attitude to their subject that creates the geek.
Geeks and Nerds are closely related, in fact many nerds will start out as geeks - a starter techie if you will. Geek shouldn't be a negative term, as it merely infers knowledge. Nerd is more negative, mainly due to the unhealthy obsessive nature of the classic Nerd, however the benefit a Nerd can have on a subject should not be overlooked either.
Viva La Difference!
Of course making your own definition of Geeks and Nerds certainly qualifies you for one of the categories… which one is up to you…