null vs void

null and void both are nouns.

Word	Noun	Adjective	Verb	Adverb
null	Yes	Yes	No	No
void	Yes	Yes	Yes	No

As adjectives, null and void are synonyms defined as:

null (noun)	void (noun)
a quantity of no importance; thing (object:), singular, negative pronoun; pronoun, thing, singular; quantifier: negative existential	an empty area or space
	the state of nonexistence

null (adjective)	void (adjective)
lacking any legal or binding force	containing nothing
	lacking any legal or binding force

null (verb)	void (verb)
	excrete or discharge from the body
	take away the legal force of or render ineffective
	clear (a room, house, place) of occupants or empty or clear (a place or receptacle) of something
	declare invalid