Cross breeding generally refers to the mating of two animals of different breeds. In the case of a Poodle and a Cocker Spaniel, the offspring is sometimes referred to as a Cockapoo. Some distinctive new breeds of cats have been created in this manner. Outcrossing refers to the breeding of two unrelated animals within the same breed.
Line breeding is the basis for establishing a good breeding program.
It is the breeding of genetically related individuals that are not closely related. An example would be the mating of two cousins. Line breeding is done to concentrate the desirable genes found within related individuals. Inbreeding is the mating of closely genetically related individuals. An example would be the breeding of a brother and sister.