heftiness vs strength

heftiness and strength both are nouns.

Word	Noun	Adjective	Verb	Adverb
heftiness	Yes	No	No	No
strength	Yes	No	No	No

As nouns, strength is a hypernym of heftiness; that is, strength is a word with a broader meaning than heftiness:

heftiness (noun)	strength (noun)
possessing muscular strength	the property of being physically or mentally strong
the property of being large in mass	an asset of special worth or utility
	permanence by virtue of the power to resist stress or force
	the amount of energy transmitted (as by acoustic or electromagnetic radiation)
	capability in terms of personnel and materiel that affect the capacity to fight a war
	physical energy or intensity
	capacity to produce strong physiological or chemical effects
	the power to induce the taking of a course of action or the embracing of a point of view by means of argument or entreaty
	the condition of financial success