Most atheists I've spoken with use the term such that theists say there is a god, atheists don't say there is a god.

Giving overlap with most (all?) agnostics.

The other, so called 'hard' atheism being seen as obviously requiring just as much devout belief as the most dogmatic of religions.

Those are out there but in my experience it's often coming less from what I think of as 'serious' and more almost nihilistic, dare I say 'edge lord' stance. Or at least one that hasn't examined itself to recognize just how much belief they exhibit, not unlike a child's unquestioning belief the toothfairy IS real.

Where it becomes often easy to start pulling apart is when you ask such a person to define god in the first place. You'll often find a caricature standing in for he concept.