Difference between Ridgid manual threaders

I have a few Ridgid pipe threading tools that I brought home last week or so:

1) Ridgid 12-R, 1/2 to 2" dies.

This is a Ridgid manual threader set.

2) A bunch of Ridgid heads 65-TC like this:

I am trying to understand what I need out of this. My own guess is that I do not really need these 65-TC heads at all, as they do not give me any bigger pipe threading capacity, and that I can do all my threading with set 1).

Am I missing anything?