razing vs tearing down

razing and tearing down both are nouns.

Word	Noun	Adjective	Verb	Adverb
razing	Yes	No	No	No
tearing down	Yes	No	No	No

As nouns, razing and tearing down are synonyms defined as:

Other synonyms of razing include demolishing, leveling.

razing (noun)	tearing down (noun)
complete destruction of a building	complete destruction of a building
the event of a structure being completely demolished and leveled