I am looking at fares for travel between JFK and SFO. I know that service on 762s is in 3 classes, and is the "flagship" service, while 763s are in two classes.

My question is this: With the 763s being upgraded to the new business class seats (being sold as first class seats domestically), why is the 763 "first" class cheaper ($519 instant upgrade fare) between SFO and JFK than the 762 (true) business class ($599 discounted business class fare), when the cheaper "first" seats (which are in fact the new business seats) on the 763s are (apparently) better than the more expensive (yet older) business seats on the 762s? Is there a difference in service/ comfort/ etc. that justifies the higher cost for business class on the 762s than first on the 763s (with their upgraded 763 business seats)?

I hope my question is clear...

I've searched for an answer to this riddle, but haven't been able to find one. thanks.