know as vs refer

know as and refer both are verbs.

Word	Noun	Adjective	Verb	Adverb
know as	No	No	Yes	No
refer	No	No	Yes	No

As verbs, refer is a hyponym of know as; that is, refer is a word with a more specific, narrower meaning than know as:

Other hyponyms of know as include baptise, baptize, christen, style, title, dub, nickname, rename, entitle, title, term, tag.

know as (verb)	refer (verb)
look on as or consider	think of, regard, or classify under a subsuming principle or with a general group or in relation to another
assign a specified (usually proper) name to	have as a meaning
	make reference to
	use a name to designate
	seek information from
	send or direct for treatment, information, or a decision
	be relevant to