rune vs grapheme

rune and grapheme both are nouns.

Word	Noun	Adjective	Verb	Adverb
rune	Yes	No	No	No
grapheme	Yes	No	No	No

As nouns, grapheme is a hypernym of rune; that is, grapheme is a word with a broader meaning than rune:

rune: any character from an ancient Germanic alphabet used in Scandinavia from the 3rd century to the Middle Ages
grapheme: a written symbol that is used to represent speech

Other hypernyms of rune include character, graph, graphic symbol.

rune (noun)	grapheme (noun)
any character from an ancient Germanic alphabet used in Scandinavia from the 3rd century to the Middle Ages	a written symbol that is used to represent speech