stance vs erectness

stance and erectness both are nouns.

Word	Noun	Adjective	Verb	Adverb
stance	Yes	No	No	No
erectness	Yes	No	No	No

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

Other hyponyms of stance include address, attention, uprightness.

stance (noun)	erectness (noun)
standing posture	the property of being upright in posture
a rationalized mental attitude	position at right angles to the horizon