The agnostic states that he/she does not, and probably cannot, know whether or not a god exists. Meanwhile, the atheist states that he/she lacks any belief in a deity. One says they don't or can't know, the other says they don't or can't believe. And yet, in daily life, both conduct themselves in much the same way. Neither the agnostic nor the atheist relies on prayer or the supernatural to get through their day. Neither the agnostic nor the atheist accepts the orthodox religious views regarding the origins or age of the Earth. And neither the agnostic nor the atheist expects things to change on this planet unless men and women alone choose to effect such change. In short, when it comes to day-to-day living, the agnostic and the atheist are more similar than they might care to admit.

When I encountered the speeches / writings of Robert Green Ingersoll, the so-called 'Great Agnostic' of the 19th Century, I found no philosophical difference between the atheist and the agnostic. Read for yourself, the essays "Individuality," "The Gods," and "Some Mistakes of Moses."