know as vs title

know as is not a noun while title is a noun.

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

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

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

know as (noun)	title (noun)
	an established or recognized right
	an informal right to something
	the name of a work of art or literary composition etc.
	a general or descriptive heading for a section of a written work
	an identifying appellation signifying status or function: e.g. `Mr.' or `General'
	an appellation signifying nobility
	a legal document signed and sealed and delivered to effect a transfer of property and to show the legal right to possess it
	a heading that names a statute or legislative bill; may give a brief summary of the matters it deals with
	(usually plural) written material introduced into a movie or TV show to give credits or represent dialogue or explain an action
	the status of being a champion

know as (verb)	title (verb)
look on as or consider	give a title to
assign a specified (usually proper) name to	designate by an identifying term