I am geek so i know how do desribe them , geek tend enjoy thing that are consider unpopular (for me its Star Wars , World of warcraft etc.) Geeks do not have to be smart , thatwould be a nerd, both nerds and geeks have friends but a geeks friends would probably say "Hey Albert i just got PvP Epic Armor on my Gnome warrior!" while a nerds friend would say "Hey Albert i just Got a A+ on my math exam.
Geek - Videogames , Sci- Fi stuff
Nerd - Brain power , school