What is the difference between an agnostic and an atheist, and which one do you identify as?

To me, the main difference is that agnostics state that they are either unsure, or will never know, whether or not there is or isn't a deity; and atheists believe in there being no deity.<br><br>But I don't know how realistic that is.<br><br>Edit: Is there a difference, or am I just trying to justify my own belief structure?