What is the difference between a canzone and an aria?

aria - a song for solo voice with instrumental accompaniment. Arias appear in cantatas, oratorios, and operas beginning in the 17trh century. Usually they emphasize musical expression more than the text. The text is often reflective, rather than descriptive of action. Arias are usually not strophic and they provide lyric interludes that temporarily pull the listener away from the action of the story.

canzone - a short, lyrical operatic song; the term itself may have originated in Provence and could have referred to arias which have no narrative quality at all, but simply reflect the singer's state of mind. Cherubino's "Voi che sapete" in Mozart's The Marriage of Figaro is called a canzone.

http://www.patriciagray.net/Operahtmls/terms.html