The Captain and Chapter Master are still pretty much the same, but their entries have been combined. The Chapter Master is now an upgrade, but maintains the same statline and Orbital Bombardment as before. The only change that I can see is that the Chapter Master is 10 points cheaper when given Terminator armor and now has access to a cheap relic blade when wearing Terminator armor.
The Librarian hasn't changed at all as far as options or wargear, but he now has access to Divination. That's a big plus, as it finally allows Space Marines to take the best buffing powers in the game without allying in a Dark Angel or Blood Angel Librarian with 5 Scouts.
The Techmarine has replaced the Master of the Forge. He retains the Master of the Forge's statline, but doesn't come with a servo-harness and is thus cheaper (when given a servo-harness, he costs the same as the old Master of the Forge). The Techmarine retains Blessing of the Omnissiah, Bolster Defenses, and the ability to take a squad of Servitors, but has lost Lord of the Armory, so he doesn't make Dreadnoughts into Heavy Support choices anymore.
The Chaplain hasn't changed much. His combi-weapon when in Terminator armor is a point cheaper, but that's it.