stance vs hard line

stance and hard line both are nouns.

Word	Noun	Adjective	Verb	Adverb
stance	Yes	No	No	No
hard line	Yes	No	No	No

As nouns, hard line is a hyponym of stance; that is, hard line is a word with a more specific, narrower meaning than stance:

Other hyponyms of stance include point of view, stand, standpoint, viewpoint.

stance (noun)	hard line (noun)
standing posture	a firm and uncompromising stance or position
a rationalized mental attitude