The answer keeps changing as SmartThings keeps rolling out new versions!
(2017 brought three: the Nvidia Shield Link, the Samsung Connect, and the SmartThings/ADT security panel.)
And the devices and features do vary somewhat.
For the most up-to-date list of hub model numbers, see the article in the community – created wiki:
Oh, and before somebody asks, as of this writing, December 2017, there is no migration tool available. If you buy a new hub, even one of the exact same model, you will have to rebuild most of your set up from scratch.
If you do happen to use webcore to set up your rules, it does have a backup feature which will help a little bit, but you will still have to move over each device individually.