I had a chance to flip thru my EMC text (Information Storage and Management, 2009 edition). In its chapter on Intelligent Storage Systems, it talks about A-A and A-P arrays by using the Clarion and Symmetrix arrays as examples of each. The book asserts that "High-end storage systems, referred to as active-active arrays, are generally aimed at" blah blah blah, and then "Midrange storage systems are also referred to as active-passive arrays and they are best suited for" blah blah blah. The book implies that A/A arrays have modular SPs that can be stacked as needed on the front-end, whereas A/P arrays have exactly two SPs. So the marketing-speak has drifted substantially from the technical, as related in this thread I found last night;
Active vs Passive vs ALUA Storage
I now have the impression that plain A/P arrays can assign some LUNs to SP-a and some to SP-b, with failover/failback capability, but assignment has to be done manually and load-balanced manually, thus the appeal of A/A.