It is a great source of irritation to Adil, when people who should know better end up using incorrect nomenclature to describe the different sexes (or none) within a species. Chickens are no exception.
Chicken is a generic term referring to both sexes. Hens are female chickens and cockerels are male. Chicks are young chickens of both sexes. All of theses terms are common British English names for the subspecies with the Latin name, Gallus gallus domesticus. Thus speaking of "chickens and cockerels" (as many do) is incorrect as it assumes that all chickens are female (which they are not otherwise they wouldn't reproduce).
As many animals enter the kitchen as a form of food, their common name tends to change. This is indeed the case for Adil's second favourite animal, cattle, which is referred to as beef when cooked. (Cattle refer to both males and females while a bull is an exclusively male word and a cow is exclusively female.) However chicken does not experience this name change, remaining chicken once cooked.
This cockerel is distinctly differnt to this hen but both are chickens