crushed rock vs gravel

crushed rock and gravel both are nouns.

Word	Noun	Adjective	Verb	Adverb
crushed rock	Yes	No	No	No
gravel	Yes	No	Yes	No

As nouns, crushed rock and gravel are synonyms defined as:

crushed rock (noun)	gravel (noun)
rock fragments and pebbles	rock fragments and pebbles

crushed rock (verb)	gravel (verb)
	be a mystery or bewildering to
	cover with gravel
	cause annoyance in; disturb, especially by minor irritations