The colonial period of United States history occurred before 1776, when America was still 13 colonies under British rule.
You can use the word colonial to describe an inhabitant of a colony ruled by another country, but you wouldn’t call a painter living in an artists' colony a colonial. On the other hand, ants, which live in ant colonies, are colonial insects. British colonial is a style of furniture the British favored for their houses and tents in India or on safari in Africa — when India and parts of Africa were British colonies.
