shoe polish vs blacking

shoe polish and blacking both are nouns.

Word	Noun	Adjective	Verb	Adverb
shoe polish	Yes	No	No	No
blacking	Yes	No	No	No

As nouns, shoe polish and blacking are synonyms defined as:

shoe polish and blacking: a substance used to produce a shiny protective surface on footwear

shoe polish (noun)	blacking (noun)
a substance used to produce a shiny protective surface on footwear	a substance used to produce a shiny protective surface on footwear