secondary vs low-level

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

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

secondary (noun)	low-level (noun)
coil such that current is induced in it by passing a current through the primary coil
the defensive football players who line up behind the linemen

secondary (adjective)	low-level (adjective)
being of second rank or importance or value; not direct or immediate	lower in rank or importance
depending on or incidental to what is original or primary	at a low level in rank or importance
inferior in rank or status	occurring at a relatively low altitude
not of major importance	not intense
belonging to a lower class or rank