So Eisen is correct, it's the same thing. A non-open access publisher could make a non-open access equivalent of PLOS ONE if they wanted to (and maybe somebody has). It's not a question of open access.
But it is worth noting that a move to APCs dramatically changes the incentive structure for a publisher, and there are built-in mechanisms in such a system to produce new strange dynamics that we haven't really seen much of before (ie the tension between needing to accept a certain volume to stay in business vs try to keep the reputation of the journal high).
Consider that PLOS ONE, because it doesn't review for importance, has a much higher acceptance rate. Only accepted papers pay processing charges, so each accepted article has to subsidize the review and rejection of all the rejected papers. In PLOS Biology or PLOS Medicine, with a low acceptance rate, each accepted article has to subsidize review of numerous other articles, driving the cost per published article way up.