Difference between EAP650s and Eap653s

I'm about to buy a few of either the 650s or the 653s and, despite my reading-up, I can't see what the difference is apart from the 650s being sold with power supplies. The prices always seem very similar and sometimes the 650s cheaper than the 653s which baffles me. I'd have thought the 650s were always more expensive. Can anyone elaborate further for me? Thanks