send a message vs pass on

send a message and pass on both are verbs.

Word	Noun	Adjective	Verb	Adverb
send a message	No	No	Yes	No
pass on	No	No	Yes	No

As verbs, pass on is a hypernym of send a message; that is, pass on is a word with a broader meaning than send a message:

Other hypernyms of send a message include communicate, pass, pass along, put across.

send a message (verb)	pass on (verb)
give or constitute a signal, not necessarily verbally	transmit information
	cause to be distributed
	move forward, also in the metaphorical sense
	give to or transfer possession of
	place into the hands or custody of
	transmit (knowledge or skills)
	refer to another person for decision or judgment