active vs existing

active is a noun but existing is not a noun.

Word	Noun	Adjective	Verb	Adverb
active	Yes	Yes	No	No
existing	No	Yes	No	No

active (noun)	existing (noun)
a person who is a participating member of an organization
the voice used to indicate that the grammatical subject of the verb is performing the action or causing the happening denoted by the verb
chemical agent capable of activity

active (adjective)	existing (adjective)
(used of verbs (e.g. `to run') and participial adjectives (e.g. `running' in `running water')) expressing action rather than a state of being	having existence or being or actuality
characterized by energetic activity	presently existing
tending to become more severe or wider in scope	existing in something specified
disposed to take action or effectuate change
(of e.g. volcanoes) erupting or liable to erupt
(of e.g. volcanoes) capable of erupting
full of activity or engaged in continuous activity
exerting influence or producing a change or effect
engaged in full-time work
expressing that the subject of the sentence has the semantic function of actor:
(of the sun) characterized by an increased occurrence of sunspots and flares and radio emissions
in operation
taking part in an activity
engaged in or ready for military or naval operations