meat and potatoes vs foundation

meat and potatoes and foundation both are nouns.

Word	Noun	Adjective	Verb	Adverb
meat and potatoes	Yes	No	No	No
foundation	Yes	No	No	No

As nouns, foundation is a hypernym of meat and potatoes; that is, foundation is a word with a broader meaning than meat and potatoes:

meat and potatoes: the fundamental part
foundation: the fundamental assumptions from which something is begun or developed or calculated or explained

Other hypernyms of meat and potatoes include base, basis, cornerstone, fundament, groundwork.

meat and potatoes (noun)	foundation (noun)
the fundamental part	the act of starting something for the first time; introducing something new
	lowest support of a structure
	a woman's undergarment worn to give shape to the contours of the body
	the fundamental assumptions from which something is begun or developed or calculated or explained
	education or instruction in the fundamentals of a field of knowledge
	an institution supported by an endowment
	the basis on which something is grounded