The American Heritage and Webster's dictionaries agreed that atheism is defined as follows:
1.) a disbelief
in or denial of the existence of God or gods.
2.) the doctrine that there is no God or gods.
3.) Godlessness; immorality.
Agnosticism was a little different. In The American Heritage dictionary, it is defined as "the doctrine that
certainty about first principles or absolute truth is unattainable and that only perceptual phenomena are objects of exact
knowledge or as the belief that there can be no proof either that God exists or that God does not exist." Webster's claims
that it is "the doctrine that the existence of a personal Deity, an unseen world, etc., can be neither proved nor disproved,
because of the necessary limits of the human mind, or because of the insufficiency of the evidence furnished by physical and
physical data, to warrant a positive conclusion."
So, according to these dictionaries, the only difference is that atheists "KNOW" that there is no God while agnostics
are just going to wait and see when they die since it can not be proven scientifically.
Or, to put it simple:
Atheist: "There is no god."
Agnostic: "I don't know and neither do you. Oh, you do? PROVE IT!