unconquerable vs impregnable

unconquerable and impregnable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unconquerable	No	Yes	No	No
impregnable	No	Yes	No	No

unconquerable (adjective)	impregnable (adjective)
not capable of being conquered or vanquished or overcome	capable of conceiving
incapable of being surmounted or excelled	immune to attack; incapable of being tampered with
	incapable of being overcome, challenged or refuted