assistant vs low-level

assistant is a noun but low-level is not a noun.

Word	Noun	Adjective	Verb	Adverb
assistant	Yes	Yes	No	No
low-level	No	Yes	No	No

assistant (noun)	low-level (noun)
a person who contributes to the fulfillment of a need or furtherance of an effort or purpose

assistant (adjective)	low-level (adjective)
of or relating to a person who is subordinate to another	lower in rank or importance
	at a low level in rank or importance
	occurring at a relatively low altitude
	not intense