The grocery stores near me sell "roasting" chickens which are bigger (more mature) and "fryer" chickens, which are younger, and smaller. I believe the "roasting" chicken meat is supposed to be a bit more flavorful. But you can roast either kind, depending on how much chicken you need. The smaller "fryers" have enough for 4. I'd say the "roasters" more like 6-7 people.
They sell them both frozen and thawed.
I'm not sure if that answered you question?