Is there a "prebiotic" that's different from "probiotic? "

Yes. While probiotics are the living bacteria that normally reside in our gut, prebiotics are the foods they eat. Prebiotics mostly come from carbohydrate fibers called oligosaccharides. You don't digest them, so the oligosaccharides remain in the digestive tract where they stimulate the growth of beneficial bacteria. Sources of oligosaccharides include fruits, legumes, and whole grains.