refresher vs potable

refresher and potable both are nouns.

Word	Noun	Adjective	Verb	Adverb
refresher	Yes	No	No	No
potable	Yes	Yes	No	No

As nouns, potable is a hypernym of refresher; that is, potable is a word with a broader meaning than refresher:

Other hypernyms of refresher include beverage, drink, drinkable.

refresher (noun)	potable (noun)
a course that reviews and updates a topic for those who have not kept abreast of developments	any liquid suitable for drinking
a drink that refreshes
a fee (in addition to that marked on the brief) paid to counsel in a case that lasts more than one day

refresher (adjective)	potable (adjective)
	suitable for drinking