1. Observe the person. Do they recite lines from "Monty Python" shows or movies, or do they occasionally throw Latin words into their dialog? Nerds are not as concerned about their level of trivial knowledge as geeks are known for embracing. Geeks often take interest in the more obscure, trivial details of life, such as noticing that your present situation is much like one from a cult-classic book or movie. Nerds will seemingly be uninterested in the details of daily life, and more focused on fantastic, scientific possibilities and the future of mankind.
2. Take a quick inventory of their prominent possessions, especially ones related to hobbies and other interests. Check for unusual objects, such as a dictionary of an obscure language, or a shelf full of anime figures. Nerds may be more willing than geeks to show off hobbies and possessions that flaunt their intellect, where as geeks may take pride in more obscure and unique subjects.
3. Engage the person in conversation. If the person fails to respond in a socially comfortable manner (ie: they make you nervous, or vice versa), you may be talking to a nerd. If they respond in a comfortable manner but appear a little 'dorky', include obscure references, and/or act silly, you might be talking to a geek. Also, nerds may speak in layman's terms for your benefit because you may not understand the basic concepts of their area interest. Geeks may speak in detail about their own interests, unconcerned with whether or not you truly comprehend it.
4. Inquire about the person's interests. Hobbies involving Calculus, Quantum Physics, and other theoretical sciences are good indications of a nerd, while an obsession with Japanese Manga or some form of technology puts them in line with a geek.
More in WikiHow
BTW After going through this steps, it's clear, I'm a geek!