What is the difference between Dirt and Soil when it comes to Life Support?

[Xtra]

There are several mods in the game which have greenhouse or Snack creation, and several that contain Soil, but when I try to gather/load it in the VAB, I can't find Soil and (maybe just my level) I don't see a Converter for it.  I can load up on Dirt, but I can't seem to find soil.   Then I ran into a post that says Soil is a biproduct of the Kerbals eating Snacks... which makes me believe they're talking about kerbal bodily waste.

So I guess that's pretty much what I'm trying to figure out... is Soil the biproduct of Kerbals eating or is it converted Dirt and maybe fertilizer?

[JadeOfMaar]

@Xtra Dirt is primarily a mined resource that's used by MKS' ISRU chains. It's a low-grade alt to stock Ore (literally, low-grade ore) and represents the continuous but tiny presence of all other crustal resources that you happen to need and do exist on the current planet but might not exist in the current biome. MKS has parts and processes for sifting Dirt. If you don't use MKS then help yourself and write a converter recipe for yourself for (inefficiently) splitting Dirt into whatever you need.

Soil is primarily the waste resource of the Snacks! LS mod (equivalent to Mulch in USI LS) but is treated differently by another mod who's name I can't remember and I don't think it's a LS mod. Part of how Snacks works is that it adds the Soil Recycler converter to some stock parts (namely the Hitchhiker can) and it adds resources to crewed parts at the points of reloading a craft file in the editor or launching from the editors. I don't think it adds Soil tankage to every affected part so be mindful of that. Snacks! adds a few 1.25m tanks (they look like the un-Restocked FL-Tx00's. Can't miss the green on them) which are switchable between Snacks and/or Soil. They'll be in either the Utility or Payload? category or the CCK LS category.

Soil is not a CRP resource, I think, so expect it to be inaccessible without the mods that use it.