under vs below

under is an adjective but below is not an adjective.

Word	Noun	Adjective	Verb	Adverb
under	No	Yes	No	Yes
below	No	No	No	Yes

As adverbs, under and below are synonyms defined as:

under (adjective)	below (adjective)
located below or beneath something else
lower in rank, power, or authority

under (adverb)	below (adverb)
further down	(in writing) at a later place
down below	in or to a place that is lower
below the horizon	further down
below some quantity or limit	on a floor below
in or into a state of subordination or subjugation
down to defeat, death, or ruin
into unconsciousness
through a range downward