I imagine there will be different tiers of A series chips when they start shipping them in Macs. The MBA will probably get basically the same chip they will be putting in the iPad Pro, with around the same power envelope and passive cooling. MBP will probably get more cores running at higher clock speeds and more graphics performance (I still haven't figured out if they are going to make much larger chips with Apple graphics or still pair their chips with AMD discrete graphics), but in a higher power envelope with active cooling. So to answer your question the MBA fills a lower price slot than the MBP - without having to pay for expensive Intel chips they may be able to lower the price of the MBA a bit more.