open vs gap

open and gap both are nouns.

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

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

open (noun)	gap (noun)
information that has become public	an act of delaying or interrupting the continuity
a tournament in which both professionals and amateurs may play	a narrow opening
a clear or unobstructed space or expanse of land or water	a conspicuous disparity or difference as between two figures
where the air is unconfined	a difference (especially an unfortunate difference) between two opinions or two views or two situations
	an open or empty space in or between things
	a pass between mountain peaks; geomorphological term for the lowest point on a mountain ridge between two peaks

open (adjective)	gap (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

open (verb)	gap (verb)
make available	make an opening or gap in
become available
make the opening move
cause to open or to become open
become open
spread out or open from a closed or folded state
display the contents of a file or start an application as on a computer
afford access to
start to operate or function or cause to start operating or functioning
begin or set in action, of meetings, speeches, recitals, etc.
have an opening or passage or outlet