pourboire vs fringe benefit

pourboire and fringe benefit both are nouns.

Word	Noun	Adjective	Verb	Adverb
pourboire	Yes	No	No	No
fringe benefit	Yes	No	No	No

As nouns, fringe benefit is a hypernym of pourboire; that is, fringe benefit is a word with a broader meaning than pourboire:

pourboire: a relatively small amount of money given for services rendered (as by a waiter)
fringe benefit: an incidental benefit awarded for certain types of employment (especially if it is regarded as a right)

Other hypernyms of pourboire include perk, perquisite.

pourboire (noun)	fringe benefit (noun)
a relatively small amount of money given for services rendered (as by a waiter)	an incidental benefit awarded for certain types of employment (especially if it is regarded as a right)