As a food, chickens are classified by the age of the bird. Fryers and roasters are two classifications of chicken, each with its own characteristics.
Age
Fryer chickens are 7 to 13 weeks old, while roaster chickens are 3 to 5 months old.
Size
Fryer chickens weigh between 1 1/2 and 4 lbs. Roasters are larger and weigh between 3 1/2 and 7 lbs.
Serving Size
A whole fryer chicken is typically enough food to serve three to four people, and a roaster chicken serves between five and seven people.
Flavor
The meat of a roaster chicken is typically more flavorful than a fryer.
Tender
While roaster meat is tender as well, the meat of the fryer chicken is especially tender.