overturn vs bring down

overturn is a noun but bring down is not a noun.

Word	Noun	Adjective	Verb	Adverb
overturn	Yes	No	Yes	No
bring down	No	No	Yes	No

As verbs, overturn and bring down are synonyms defined as:

Other synonyms of overturn include overthrow, subvert.

overturn (noun)	bring down (noun)
the act of upsetting something
an improbable and unexpected victory

overturn (verb)	bring down (verb)
change radically	cut down on; make a reduction in
rule against	impose something unpleasant
cancel officially	cause to be enthusiastic
turn from an upright or normal position	cause to come to the ground
cause to overturn from an upright or normal position	move something or somebody to a lower position
cause the downfall of; of rulers	cause the downfall of; of rulers