co-occurrent vs synchronous

co-occurrent and synchronous both are adjectives.

Word	Noun	Adjective	Verb	Adverb
co-occurrent	No	Yes	No	No
synchronous	No	Yes	No	No

co-occurrent (adjective)	synchronous (adjective)
occurring or operating at the same time	occurring or existing at the same time or having the same period or phase
	(digital communication) pertaining to a transmission technique that requires a common clock signal (a timing reference) between the communicating devices in order to coordinate their transmissions