covering vs crust

covering and crust both are nouns.

Word	Noun	Adjective	Verb	Adverb
covering	Yes	No	No	No
crust	Yes	No	Yes	No

As nouns, crust is a hyponym of covering; that is, crust is a word with a more specific, narrower meaning than covering:

covering (noun)	crust (noun)
the act of protecting something by covering it	the trait of being rude and impertinent; inclined to take liberties
the work of applying something	the outer layer of the Earth
the act of concealing the existence of something by obstructing the view of it	a hard outer layer that covers something
an artifact that covers something else (usually to protect or shelter or conceal it)
a natural object that covers or envelops

covering (verb)	crust (verb)
	form a crust or form into a crust