You see the bolded part there? This is what makes it a totally different subject from atheism. Atheism itself has no opinion about whether or not the nature of deities is knowable.: a person who holds the view that any ultimate reality (as God) is unknown and probably unknowable; broadly : one who is not committed to believing in either the existence or the nonexistence of God or a god
Such a distinction absolutely exists so long as the person contemplating it is intelligent enough to understand it.
There are plenty of ways a deity-like entity or system could potentially work that can't be excluded, and there are also millions of non-described possible deities that can't be excluded either.