A catalog is a book that lists many things: the most common type of catalog is for a store.
A catalog is an organized list that appears in book or pamphlet form. The Sears catalog tells you all the things you can buy at Sears, along with pictures of the items and what they cost. But you can also use catalog to mean any kind of listing. In an argument, you might say, "Why don't you just make a catalog of all my faults!" When you're making a catalog of any kind, you're cataloging.