What is the difference between a stool softener like colace (docusate sodium) and a laxative?

Softener vs laxative. There are many different ways to deal w/constipation, starting 1st w/fiber, fluids & exercise. Failing that, stool softeners do exactly that - soften stool, typically by increasing water content. Laxatives OTOH irritate bowel into having a bowel movement. Check out http://www.mayoclinic.org/diseases-conditions/constipation/in-depth/laxatives/art-20045906.