undetectable vs indiscernible

undetectable and indiscernible both are adjectives.

Word	Noun	Adjective	Verb	Adverb
undetectable	No	Yes	No	No
indiscernible	No	Yes	No	No

As adjectives, undetectable and indiscernible are synonyms defined as:

Other synonyms of undetectable include insensible.

undetectable (adjective)	indiscernible (adjective)
barely able to be perceived	difficult or impossible to perceive or discern
not easily seen	barely able to be perceived