Not unusually, for a gastronomy based organisation, there are a lot of people from the food and drink industry in Slow Food. Chefs, cooks, restaurateurs, shop owners, food writers, artisan producers, farmers and growers, who form the producers.
Then there are all the people who are not directly involved in the industry but have an interest in where their food comes from, in supporting locally produced food and in the general enjoyment of good food. These people are what Slow Food founder Carlo Petrini refers to as co-producers.
Co-producers are the people without whom the producers would not have any business. Slow Food members like to get to know the producers, and by supporting them through buying their products, they have a stake in the production; hence the name co-producers. You can't really separate producers from co-producers.