A franchise is an enterprise where the entire business model is set up for you; the franchise manager has very little say in how things are done. For instance, a franchise, though privately owned, is automatically included in chain-wide changes of merchandise, chain-wide sales and promotions, and chain-wide management adjustments.
A dealership is an agreement to sell a specific product or product line, but most of the decisions on how to go about that are up to the dealership manager. A dealership can hold a sale, change its profit margin, do its own advertising, or adjust its offerings, where a franchise usually can't.
As a result, the manager of a franchise is enforcing decisions that are made by the chain, whereas the manager of a dealership has more latitude and can make more decisions directly.
Here is a link to a good article that explains the differences between the two.