cover charge vs fixed cost

cover charge and fixed cost both are nouns.

Word	Noun	Adjective	Verb	Adverb
cover charge	Yes	No	No	No
fixed cost	Yes	No	No	No

As nouns, fixed cost is a hypernym of cover charge; that is, fixed cost is a word with a broader meaning than cover charge:

cover charge: a fixed charge by a restaurant or nightclub over and above the charge for food and drink
fixed cost: a periodic charge that does not vary with business volume (as insurance or rent or mortgage payments etc.)

Other hypernyms of cover charge include fixed charge, fixed costs.

cover charge (noun)	fixed cost (noun)
a fixed charge by a restaurant or nightclub over and above the charge for food and drink	a periodic charge that does not vary with business volume (as insurance or rent or mortgage payments etc.)