Hi Marie
If you do a search on the forum, you'll find lots of threads on Working Cockers which will give you more info but basically, a Working Cocker comes from lines specifically bred to produce working gundogs. If you look at a Working Cocker pedigree, you'll usually see some dogs with the title FT CH, meaning Field Trial Champion whereas if you look at a show-type pedigree, you'll see some dogs with the title SH CH meaning Show Champion. There are also big differences in appearance between the Working & show-type Cocker (previous threads on the subject will tell you more about these differences)
Jane