brain vs subconscious

brain and subconscious both are nouns.

Word	Noun	Adjective	Verb	Adverb
brain	Yes	No	Yes	No
subconscious	Yes	Yes	No	No

As nouns, subconscious is a hyponym of brain; that is, subconscious is a word with a more specific, narrower meaning than brain:

brain: that which is responsible for one's thoughts, feelings, and conscious brain functions; the seat of the faculty of reason
subconscious: psychic activity just below the level of awareness

Other hyponyms of brain include noddle, tabula rasa, ego, unconscious, unconscious mind, subconscious mind.

brain (noun)	subconscious (noun)
that part of the central nervous system that includes all the higher nervous centers; enclosed within the skull; continuous with the spinal cord	psychic activity just below the level of awareness
mental ability
that which is responsible for one's thoughts, feelings, and conscious brain functions; the seat of the faculty of reason
the brain of certain animals used as meat
someone who has exceptional intellectual ability and originality

brain (adjective)	subconscious (adjective)
	just below the level of consciousness

brain (verb)	subconscious (verb)
hit on the head
kill by smashing someone's skull