impregnable vs unconquerable

impregnable and unconquerable both are adjectives.

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

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