Prebiotics are substances that serve as food for intestinal bacteria, such as oligosaccharides.
On the other hand, probiotics are "live microbial organisms that have a positive effect on health by improving the balance of intestinal flora," and include live bacterial preparations such as Lactobacillus (lactic acid bacteria) and Bifidobacterium (bifidobacteria), as well as yogurt.
By taking both, you can expect to see benefits such as intestinal regulation, improved immunity, allergy relief, and improved sleep.