substance vs solidness

substance and solidness both are nouns.

Word	Noun	Adjective	Verb	Adverb
substance	Yes	No	No	No
solidness	Yes	No	No	No

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

substance (noun)	solidness (noun)
the real physical matter of which a person or thing consists	the quality of being substantial or having substance
a particular kind or species of matter with uniform properties	the quality of being solid and reliable financially or factually or morally
the property of holding together and retaining its shape	the consistency of a solid
the idea that is intended	the state in which a substance has no tendency to flow under moderate stress; resists forces (such as compression) that tend to deform it; and retains a definite size and shape
the choicest or most essential or most vital part of some idea or experience
content communicating a message; what something is about
considerable capital (wealth or income)
material of a particular kind or constitution