Profantasy's Fractal Terrains 3 & 3
I don't understand your question. Which of the product versions are you referring to: "Fractal Terrains" (V 1.x), "Fractal Terrains Pro" (V 2.x), or "Fractal Terrains 3" (V 3.x)? There are quite a few changes between major versions and a fair number of minor versions, as well. I think that the product readme has (or used to have) a version history in it. It'd take me a while to tease out what all of the features were for each version released in the last 14 years and I'm not sure how helpful that would be (admittedly, it would help the folks out there torrenting the product to figure out which version they might want to download).
FTPro 2.2 and whatever the most recent version of 3 is.
I asked the great oracle this question:
and received this answer (among others):
So it's mostly a performance-enhanced version for multicore with a few nice features tacked on (and a huge stack of bug fixes, some of which do nasty things to your worlds). It is rumored that there is a 64-bit unsupported beta version of FT3 that can be obtained from the product's developer if you ask nicely.