Are laxatives the same as stool softeners, or are they two separate things?
Well, there are several kinds of laxatives.
Some can stimulate the bowel. Osmotics pull liquid together to soften poo, similar to how it happens if left in the toilet. Stool softeners help water and fat get absorbed into poo. Mineral oil slickens it to slide out (apparently, don’t use mineral oil with Senacot, though, and I would imagine it is like water and oil to use it with Miralax, so that probably doesn’t help). Dietary fiber has several ways of working, between soluble and insoluble fiber.
More on those, here:
https://www.health.harvard.edu/diseases-and-conditions/dont-bomb-the-bowel-with-laxatives
I hope that helps.