For one, there seems to be a form of XP loss on death (though not for avatars below level 10). CBT5 also marks the introduction of the game's trial system, so all you naughty-by-nature folks will likely find out what sort of crime and punishment await you in XL's fantasy sandbox. Finally, there are bits about crop growth and how climate affects it as well as some verbiage about certain regional tradeskill specialties.
Massively's got a couple of folks patching up CBT5 as we speak, so look for some up-to-the-minute ArcheAge impressions in the coming weeks.
[Thanks to Dengar for the tip!]