As nouns the difference between grapheme and allograph
is that grapheme is a fundamental unit of a writing system, corresponding to (for example) letters in the English alphabet or jamo in Korean Hangeul while allograph is a variant form of a letter (or other grapheme.
grapheme
English
Noun
(
en noun)
A fundamental unit of a writing system, corresponding to (for example) letters in the English alphabet or jamo in Korean Hangeul.
In alphabetic writing, the shortest group of letters composing a phoneme.
allograph
English
Noun
(
en noun)
A variant form of a letter (or other grapheme)
A signature made by one person for another (compare autograph)