When a company introduces a line or collection of fabric there can be any number of prints from a minimum five or six on up. You can think of the lines of fabric in two categories. There are the standard lines such as solids and blenders and checkers and paisley and so on. These are subjects and patterns that are always in demand, the standards, the foundations if you will. These manufactures keep in stock and will reproduce as demand dictates.
Then, there are the novelty prints. Novelty prints are the things that may go in and out of vogue, things like cars or animals, popular movies, sports teams, cartoon characters and the like. Generally, these are considered one and done runs. the manufactures will produce one batch and then the production dies are done away with. It may be a number of years before the subject comes back in fashion and similar prints are produced. In other words, get them when you see them or you might have trouble finding them.
A line of fabric might be the same print/pattern in different colors or with a common theme that are complimentary and go well together. Some collections become well know and in this group, you will find the different prints that make up that collection or line.