No they don't. Whoever wrote this is wrong.
The prefix 'a' denotes a lack of and not an explicit denial of God's existence, agnosticism is not a more 'humble' view to take than atheism, and this "unlike the classic atheist, the agnostic is less likely to be driven by beliefs." is absolute garbage.
Theism is the claim that a God exists. Atheism is the lack of belief in that claim, usually due to the fact that there is no credible evidence to support it up and a truckload to show that the religions that claim to explain God are utterly wrong. Claiming that God does not exist is technically a logical fallacy, as it is unprovable, but so is claiming that unicorns or fairies don't exist.
As I said, it's an distinction invented by people such as you to try and cast certain connotations on certain words because you can't accept the facts of reality.