aleatory music vs art movement

aleatory music and art movement both are nouns.

Word	Noun	Adjective	Verb	Adverb
aleatory music	Yes	No	No	No
art movement	Yes	No	No	No

As nouns, art movement is a hypernym of aleatory music; that is, art movement is a word with a broader meaning than aleatory music:

aleatory music: 20th-century music in which chance or indeterminate elements are left for the performer to realize.
art movement: a group of artists who agree on general principles

Other hypernyms of aleatory music include artistic movement.

aleatory music (noun)	art movement (noun)
20th-century music in which chance or indeterminate elements are left for the performer to realize.	a group of artists who agree on general principles