sum vs bare bones

sum and bare bones both are nouns.

Word	Noun	Adjective	Verb	Adverb
sum	Yes	No	Yes	No
bare bones	Yes	No	No	No

As nouns, bare bones is a hyponym of sum; that is, bare bones is a word with a more specific, narrower meaning than sum:

sum: the choicest or most essential or most vital part of some idea or experience
bare bones: (plural) the most basic facts or elements

Other hyponyms of sum include hypostasis, haecceity, quiddity, quintessence, stuff.

sum (noun)	bare bones (noun)
the whole amount	(plural) the most basic facts or elements
the choicest or most essential or most vital part of some idea or experience
a quantity obtained by the addition of a group of numbers
the final aggregate
a set containing all and only the members of two or more given sets
a quantity of money

sum (verb)	bare bones (verb)
determine the sum of
be a summary of