open vs embark on

open is a noun but embark on is not a noun.

Word	Noun	Adjective	Verb	Adverb
open	Yes	Yes	Yes	No
embark on	No	No	Yes	No

As verbs, embark on is a hypernym of open; that is, embark on is a word with a broader meaning than open:

Other hypernyms of open include commence, start, start up.

open (noun)	embark on (noun)
information that has become public
a tournament in which both professionals and amateurs may play
a clear or unobstructed space or expanse of land or water
where the air is unconfined

open (adjective)	embark on (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)	embark on (verb)
make available	get off the ground
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