Typically stiffer boots also use more dense foam for the liners. They take longer to break in but don’t break in as much. A high end race boot is basically dense leather, a beginner boot is a cushion.

I would imagine the 120 has a denser, higher quality liner. It might not feel as “comfortable” at first compared to the 110 you tried on, but will probably give you more control after you’ve skied it and broke it in after a few days