paving vs blacktopping

paving and blacktopping both are nouns.

Word	Noun	Adjective	Verb	Adverb
paving	Yes	No	No	No
blacktopping	Yes	No	No	No

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

paving: material used to pave an area
blacktopping: a black bituminous material used for paving roads or other areas; usually spread over crushed rock

Other hyponyms of paving include asphalt, concrete, blacktop, macadam, tarmac, tarmacadam.

paving (noun)	blacktopping (noun)
the act of applying paving materials to an area	a black bituminous material used for paving roads or other areas; usually spread over crushed rock
the paved surface of a thoroughfare
material used to pave an area