Square Enix has shared a massive info and picture dump for Final Fantasy XIV: A Realm Reborn. Head over to the official site and check out the Armoury tab to find both the Jobs and Classes sections of the site. From there you can go link diving to check out new art, screenshots, and information. There's tons to see.
For how the two relate, Square Enix says that by achieving mastery in a class, you'll be able to take on related jobs. For example, thaumaturges may aspire to become black mages; conjurers may want to work to become white mage healers.
I think these new screens are looking great. We've shared some of the better ones in our gallery.