An agnostic is someone who believes that there can be no proof of the existence of God, but does not deny the possibility that God exists: “I am confused whether is a god or not, what does that make me: an agnostic?”
An atheist, on the other hand, is a disbeliever, denier of God’s existence: “’Science and science alone is the true moving force of life, there is no god’, there are the views of my brother who is an atheist.”