sub-interval vs interval

sub-interval and interval both are nouns.

Word	Noun	Adjective	Verb	Adverb
sub-interval	Yes	No	No	No
interval	Yes	No	No	No

As nouns, interval is a hypernym of sub-interval; that is, interval is a word with a broader meaning than sub-interval:

sub-interval: an interval that is included in another interval
interval: a set containing all points (or all real numbers) between two given endpoints

sub-interval (noun)	interval (noun)
an interval that is included in another interval	the distance between things
	a set containing all points (or all real numbers) between two given endpoints
	the difference in pitch between two notes
	a definite length of time marked off by two instants