What are these different Infernal Machines from the Level 12 Infernal Machine Plan?

Solution 1:

For a level 70 Hellfire Ring you can now choose which realm you want to farm.

It is because since patch 2.0 the maximum chance of getting an organ from ubers is only 50%(comparing to 100% at MP10 before). Also, before if you only had 2 organs and you needed 1 more you had to "gamble" and open portals hoping for a right one to open first.

Now you can choose which portal to open by crafting a corresponding machine

EDIT

As you asked: a source

• Infernal Machine of Bones – Leoric and Maghda. Drops Leoric’s Regret organ.
• Infernal Machine of War – Siegebreaker and Zoltan Kulle. Drops Idol of Terror organ.
• Infernal Machine of Gluttony – Rakanoth and Ghom. Drops Vial of Putridness organ.
• Infernal Machine of Evil – Diablo and random Ubers. Drops Heart of Evil organ.