porter's beer vs porter

porter's beer and porter both are nouns.

Word	Noun	Adjective	Verb	Adverb
porter's beer	Yes	No	No	No
porter	Yes	No	Yes	No

As nouns, porter's beer and porter are synonyms defined as:

porter's beer and porter: a very dark sweet ale brewed from roasted unmalted barley

porter's beer (noun)	porter (noun)
a very dark sweet ale brewed from roasted unmalted barley	a very dark sweet ale brewed from roasted unmalted barley
	a person employed to carry luggage and supplies
	a railroad employee who assists passengers (especially on sleeping cars)
	someone who guards an entrance

porter's beer (verb)	porter (verb)
	carry luggage or supplies