open vs subject

open and subject both are nouns.

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

As adjectives, open and subject are synonyms defined as:

Other synonyms of open include capable.

open (noun)	subject (noun)
information that has become public	something (a person or object or scene) selected by an artist or photographer for graphic representation
a tournament in which both professionals and amateurs may play	a branch of knowledge
a clear or unobstructed space or expanse of land or water	some situation or event that is thought about
where the air is unconfined	the subject matter of a conversation or discussion
	(grammar) one of the two main constituents of a sentence; the grammatical constituent about which something is predicated
	(logic) the first term of a proposition
	a person who owes allegiance to that nation
	a person who is subjected to experimental or other observational procedures; someone who is an object of investigation

open (adjective)	subject (adjective)
ready or willing to receive favorably	likely to be affected by something
affording unobstructed entrance and exit; not shut or closed	being under the power or sovereignty of another or others
affording free passage or access	possibly accepting or permitting
(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)	subject (verb)
make available	make accountable for
become available	cause to experience or suffer or make liable or vulnerable to
make the opening move	make subservient; force to submit or subdue
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