
Labradors are in the Gundog Group. so in shows run on the Group system, all best of breed winnewrs in their respecitve groups compete for best in Group, and then the Group winners compete against each other for Best in show.
In each breed there may be one or more breed classes. At championship shows they will be split by sex. You will have at champ shows at least a Puppy, Junior, Post Graduat, limit and Open class for each sex, when CCs are on offer. Each class will be judged, then the winners will compete against each other to determine Best of sex, and then Best of Breed.