caution vs warning

caution and warning both are nouns.

Word	Noun	Adjective	Verb	Adverb
caution	Yes	No	Yes	No
warning	Yes	Yes	No	No

As nouns, warning is a hypernym of caution; that is, warning is a word with a broader meaning than caution:

caution (noun)	warning (noun)
the trait of being cautious; being attentive to possible danger	a message informing of danger
the trait of being circumspect and prudent	cautionary advice about something imminent (especially imminent danger or other unpleasantness)
judiciousness in avoiding harm or danger	notification of something, usually in advance
a warning against certain acts

caution (adjective)	warning (adjective)
	serving to warn

caution (verb)	warning (verb)
warn strongly; put on guard