soul vs soulfulness

soul and soulfulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
soul	Yes	No	No	No
soulfulness	Yes	No	No	No

As nouns, soul and soulfulness are synonyms defined as:

soul (noun)	soulfulness (noun)
a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential	deep feeling or emotion
the human embodiment of something
a secular form of gospel that was a major Black musical genre in the 1960s and 1970s
deep feeling or emotion
the immaterial part of a person; the actuating cause of an individual life