tumulus vs barrow

tumulus and barrow both are nouns.

Word	Noun	Adjective	Verb	Adverb
tumulus	Yes	No	No	No
barrow	Yes	No	No	No

As nouns, tumulus and barrow are synonyms defined as:

tumulus and barrow: (archeology) a heap of earth placed over prehistoric tombs

Other synonyms of tumulus include burial mound, grave mound.

tumulus (noun)	barrow (noun)
(archeology) a heap of earth placed over prehistoric tombs	a cart for carrying small loads; has handles and one or more wheels
	(archeology) a heap of earth placed over prehistoric tombs
	the quantity that a barrow will hold