X-heads vs J-heads: what's the difference??

We have a member that posted these for sale.....Now, we're all nice guys here, and I wont comment on these. So if you comment, please be civil. :D

http://www.forabodiesonly.com/mopar/showthread.php?t=262890

I will be nice...........
It must be because rent money is 4X in CA so parts must be too.