Upgrades is any security or big fix as well. Those tend to be quite safe in point release distros. Upgrading to a new point release version is has all the same problems the rolling release had over the same period all bundle in one messy upgrade (which makes them a huge pain to deal with as they often compound). But between those, the patch upgrades tend to be quite smooth.

I would say the over a longer time period rolling release break in bigger way less often. But they tend to have more but smaller breakages that are easy to trivial to fix.