rune vs runic letter

rune and runic letter both are nouns.

Word	Noun	Adjective	Verb	Adverb
rune	Yes	No	No	No
runic letter	Yes	No	No	No

As nouns, rune and runic letter are synonyms defined as:

rune and runic letter: any character from an ancient Germanic alphabet used in Scandinavia from the 3rd century to the Middle Ages

rune (noun)	runic letter (noun)
any character from an ancient Germanic alphabet used in Scandinavia from the 3rd century to the Middle Ages	any character from an ancient Germanic alphabet used in Scandinavia from the 3rd century to the Middle Ages