A song is a musical composition performed by the human voice. The voice often carries the melody using patterns of sound and silence. Songs have a structure, such as the common ABA form, and are usual
American jazz singer and songwriter Billie Holiday in New York City in 1947
In music, an aria is a self-contained piece for one voice, with or without instrumental or orchestral accompaniment, normally part of a larger work.
The farewell aria of Sultan Bajazet in Handel's opera Tamerlano (note the da capo instruction). First edition, London, 1719.