The words archaic and ancient are synonyms, but do differ in nuance. Specifically, archaic implies having the character or characteristics of a much earlier time.

// the play used archaic language to convey a sense of period

Some common synonyms of ancient are antiquated, antique, archaic, obsolete, old, and venerable. While all these words mean "having come into existence or use in the more or less distant past," ancient applies to occurrence, existence, or use in or survival from the distant past.

// ancient accounts of dragons

Although the words antique and ancient have much in common, antique applies to what has come down from a former or ancient time.

// collected antique Chippendale furniture