tallness vs loftiness

tallness and loftiness both are nouns.

Word	Noun	Adjective	Verb	Adverb
tallness	Yes	No	No	No
loftiness	Yes	No	No	No

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

tallness: the vertical dimension of extension; distance from the base of something to the top
loftiness: the quality of being high or lofty

Other hyponyms of tallness include highness, lowness.

tallness (noun)	loftiness (noun)
the vertical dimension of extension; distance from the base of something to the top	the quality of being high or lofty
the property of being taller than average stature	impressiveness in scale or proportion