They are: creature, land, instant, sorcery, artifact, enchantment, planeswalker, battle, and kindred
Aside from doing broken things with Gerrard, theres still plenty of excitement to reinforce existing decks as a recursion piece
They have vastly different progression systems, economies, user interfaces and design goals, as well as a 17-year gap between their release dates
Wrenn and Seven is a boon to lands-based decks, and Im seeing it do a lot of work in Lord Windgrace or any Omnath build
This never adds to the board on it's own, but presumably the cards it draws you will help you add to the board on subsequent turns and the drain life effect is nuts with Mobilize
Seven rares and seven mythic raresincluding the three mythic planeswalkersappear in borderless versions with alternate art