There are essentially four generational variations of the Cockapoo hybrid: F1, F1B, F2 and F3. Although variations subsequent to the F3 may eventually occur (most breed clubs and kennels tend to formally recognize a hybrid as a purebred once the breeding variation reaches F7, which is when the "hybrid vigor" of crossbred dogs is gone), there is presently very little demand for the F4 and beyond.
The F1 is produced by breeding a Cocker Spaniel with a Poodle, and the size variation that occurs with the F1 Cockapoo is determined by the breed and size variations of the two purebred dogs. As there are many breeds and dog group variations of Cocker Spaniel (American "show" or "working" Cocker Spaniels and English "show" or "working" Cocker Spaniels are the four Spaniel breed/variations most often used) and three size variations of Poodle (Toy, Miniature and Standard), there is room for a lot of variety in the F1 alone. An F1B Cockapoo is bred by crossing an F1 Cockapoo with either a Cocker Spaniel or a Poodle. The F1B is where it can get interesting and where the Cockapoo characteristics can be better controlled, for the type of breed with which the Cockapoo is "bred back" (the Cocker Spaniel or the Poodle) can determine greatly the size, coat style and other traits. (Likewise, an F2B Cockapoo is produced when an F2 Cockapoo is bred back with a Spaniel or Poodle, and so on down the line with F3B, etc.)
The F2 Cockapoo is produced by cross-breeding two F1 Cockapoos, the F3 comes from breeding two F2s, and so on.
Regarding coat types, a Cockapoo may develop one of these three styles: a soft, silky, ringlet-styled coat; a slightly less soft coat with tight curls; or a straight coat. The Cockapoo coat type may often be determined as early as when a pup is around six weeks old — but determining this is usually best done by an experienced breeder as well as one who knows whether the pup was an F1, F1B, etc. The ringlet coat tends to be very low-shedding, have little dander and be nearly allergen-free as well as be relatively low-maintenance. The tight curl coat will require a moderate amount of maintenance for while it too is low-shedding and practically free of dander and allergens, it will grow a lot and get thick if not trimmed regularly. The straight coat is also a low-shedding, almost allergen- and dander-free coat that will need a little more maintenance than the ringlet coat but less than the tight curl one.
Like the Poodle — which is recognized as a single breed but with three variations therein — the Cockapoo is recognized by breeders and dog lovers in three size variations: Toy, Miniature and Standard. Because the Cockapoo is usually produced to be small, Toys and Miniature Cockapoos are almost the only variations bred. Toy Cockapoos are 10" tall or less, and Mini Cockapoos are 11" - 14" tall. Cockapoos that are 15" or taller are Standard Cockapoos. (It should be noted that the American Kennel Club (AKC) does not recognize "Teacup" as a size; if the Poodle parent is 10" or less in height, then it's simply a Toy Poodle. As such, Teacup"Cockapoos do not come from "Teacup Poodles," although very small Cockapoos may often be called "Teacups" as a selling point.)