fullness vs solidity

fullness and solidity both are nouns.

Word	Noun	Adjective	Verb	Adverb
fullness	Yes	No	No	No
solidity	Yes	No	No	No

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

Other hyponyms of fullness include repletion, satiation, satiety, excess, overabundance, surfeit, infestation.

fullness (noun)	solidity (noun)
greatness of volume	the quality of being solid and reliable financially or factually or morally
the property of a sensation that is rich and pleasing	the consistency of a solid
the condition of being filled to capacity	state of having the interior filled with matter
completeness over a broad scope