start vs open

start and open both are nouns.

Word	Noun	Adjective	Verb	Adverb
start	Yes	No	Yes	No
open	Yes	Yes	Yes	No

As verbs, open is a hyponym of start; that is, open is a word with a more specific, narrower meaning than start:

Other hyponyms of start include inaugurate, kick off.

start (noun)	open (noun)
the act of starting something	information that has become public
a sudden involuntary movement	a tournament in which both professionals and amateurs may play
a turn to be a starter (in a game at the beginning)	a clear or unobstructed space or expanse of land or water
the advantage gained by beginning early (as in a race)	where the air is unconfined
a signal to begin (as in a race)
the beginning of anything
a line indicating the location of the start of a race or a game
the time at which something is supposed to begin

start (adjective)	open (adjective)
	ready or willing to receive favorably
	affording unobstructed entrance and exit; not shut or closed
	affording free passage or access
	(set theory) of an interval that contains neither of its endpoints
	open and observable; not secret or hidden
	used of mouth or eyes
	ready for business
	not having been filled
	(of textures) full of small openings or gaps
	openly straightforward and direct without reserve or secretiveness
	not requiring union membership
	open to or in view of all
	possibly accepting or permitting
	without undue constriction as from e.g. tenseness or inhibition
	having no protecting cover or enclosure
	affording free passage or view
	with no protection or shield
	accessible to all
	not sealed or having been unsealed
	not brought to a conclusion; subject to further thought
	not defended or capable of being defended

start (verb)	open (verb)
take the first step or steps in carrying out an action	make available
set in motion, cause to start	become available
play in the starting lineup	make the opening move
bring into being	cause to open or to become open
get off the ground	become open
begin or set in motion	spread out or open from a closed or folded state
get going or set in motion	display the contents of a file or start an application as on a computer
depart for someplace	afford access to
bulge outward	start to operate or function or cause to start operating or functioning
move or jump suddenly, as if in surprise or alarm	begin or set in action, of meetings, speeches, recitals, etc.
begin work or acting in a certain capacity, office or job	have an opening or passage or outlet
begin an event that is implied and limited by the nature or inherent function of the direct object
have a beginning, in a temporal, spatial, or evaluative sense
have a beginning characterized in some specified way