Atheism and agnosticism are generally seen as being related and often as synonymous. Yet, strictly speaking, atheism denies God's existence, while agnosticism remains neutral about it.
Sometimes confusion arises in discussions or debates, when one side uses a different definition from another side. This can be used as a deliberate tactic.
Let us be clear, anyway, about the two different positions, regardless of terminology:
Most writers call the first position "atheism" and the second position "agnosticism".
However, the term atheism is used interchangeably by some authors for both positions! For these writers, atheism is "lack of belief in God". It does not matter to them whether this lack of belief stems from repudiation or open mindedness.