What is the difference between laxative , purgative and cathartic?

Laxatives make defecation easier . Purgatives cause bowels to evacuate everything from them. Cathartics make urgency to defecate sooner.

Laxatives are agents that add bulk to intestinal contents, that retain water within the bowel lumen by virtue of osmotic effects, or that stimulate intestinal secretion or motility, thereby increasing the frequency and ease of defecation.

laxatives - end with soft stool(it is the evacuation of formed fecal material)

cathartics - end with more liquid or fluidly stool(evacuation of unformed watery fecal material)