I asked Kiya about the product descriptions and got a pretty quick response:
“The 633s-SBG is very very lightly rinsed, we still consider it "raw".
Where as the 8301 isn't rinsed at all, so there is more shrinkage there, especially for a sanforized denim.
I wouldn't expect the 633s-SBG to shrink that much, and they run a bit small so most of our clients have been sizing up.“
Sounds like the 8301 is pretty much an unwashed sanforized fabric.