greaves vs crackling

greaves and crackling both are nouns.

Word	Noun	Adjective	Verb	Adverb
greaves	Yes	No	No	No
crackling	Yes	No	No	No

As nouns, greaves and crackling are synonyms defined as:

greaves and crackling: the residue that remains after animal fat has been rendered

greaves (noun)	crackling (noun)
the residue that remains after animal fat has been rendered	the sharp sound of snapping noises
	the residue that remains after animal fat has been rendered