check character vs grapheme

check character and grapheme both are nouns.

Word	Noun	Adjective	Verb	Adverb
check character	Yes	No	No	No
grapheme	Yes	No	No	No

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

check character: a character that is added to the end of a block of transmitted data and used to check the accuracy of the transmission
grapheme: a written symbol that is used to represent speech

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

check character (noun)	grapheme (noun)
a character that is added to the end of a block of transmitted data and used to check the accuracy of the transmission	a written symbol that is used to represent speech