I don't see much difference. Do you?
But then, atheists NEVER have any internal conflicts over the nature of atheism. Just ask Ayn Rand, Karl Marx, Friedrich Nietzche, Jean Paul Sartre, Richard Dawkins, and Epicurus. I'm sure they would all agree on everything.
All atheists are exactly the same, just like all Christians, all Muslims, and all Jews.
... identical as penguins.
As my friend David Kaplan says, the Rightwing Hegelians met the Leftwing Hegelians at Stalingrad and tried to murder each other. Neither side could be accused of religious sympathies.
Perhaps the reason people murder each other with such relish over matters of belief has to do with something other than any particular creed.
As Hannah Arendt pointed out, all ideologues, no matter what they believe, are potential murderers.
As a friend of mine always said (I think accurately) fanatics are all the same. What they believe or don't believe doesn't matter in the end.
Believers and unbelievers come in all kinds of varieties and nuances, as many as there are people.
But fanatics are all the same.