turn over vs overturn

turn over is not a noun while overturn is a noun.

Word	Noun	Adjective	Verb	Adverb
turn over	No	No	Yes	No
overturn	Yes	No	Yes	No

As verbs, turn over and overturn are synonyms defined as:

Other synonyms of turn over include tip over, tump over.

As verbs, turn over and overturn are synonyms defined as:

turn over and overturn: cause to overturn from an upright or normal position

Other synonyms of turn over include bowl over, knock over, tip over, tump over, upset.

turn over (noun)	overturn (noun)
	the act of upsetting something
	an improbable and unexpected victory

turn over (verb)	overturn (verb)
think about carefully; weigh	change radically
turn up, loosen, or remove earth	rule against
turn upside down, or throw so as to reverse	cancel officially
turn from an upright or normal position	turn from an upright or normal position
cause to overturn from an upright or normal position	cause to overturn from an upright or normal position
move by turning over or rotating	cause the downfall of; of rulers
cause to move around a center so as to show another side of
place into the hands or custody of
do business worth a certain amount of money