apt vs tending

apt is not a noun while tending is a noun.

Word	Noun	Adjective	Verb	Adverb
apt	No	Yes	No	No
tending	Yes	Yes	No	No

As adjectives, apt and tending are synonyms defined as:

Other synonyms of apt include disposed, given, minded.

apt (noun)	tending (noun)
	the work of providing treatment for or attending to someone or something

apt (adjective)	tending (adjective)
being of striking appropriateness and pertinence	(usually followed by `to') naturally disposed toward
(usually followed by `to') naturally disposed toward
mentally quick and resourceful
at risk of or subject to experiencing something usually unpleasant