The difference between a food chain and a food web is that in a food chain you are only talking about four or five different organisms (Sun > Grass > Deer > Wolf > Worm). In a food web, you have many different organisms. Like, the sun makes the grass and the flowers grow, then the grass makes the mouse more healthy, while also doing the same for the mountain goat. Next, the mountain goat is eaten by a coyote, and the mouse is eaten by a hawk. Once the wolf and hawk are dead, the worm could decompose both.