public transport vs conveyance

public transport and conveyance both are nouns.

Word	Noun	Adjective	Verb	Adverb
public transport	Yes	No	No	No
conveyance	Yes	No	No	No

As nouns, conveyance is a hypernym of public transport; that is, conveyance is a word with a broader meaning than public transport:

Other hypernyms of public transport include transport.

public transport (noun)	conveyance (noun)
conveyance for passengers or mail or freight	act of transferring property title from one person to another
	the act of moving something from one location to another
	something that serves as a means of transportation
	the transmission of information
	document effecting a property transfer