emoji vs ideograph

emoji and ideograph both are nouns.

Word	Noun	Adjective	Verb	Adverb
emoji	Yes	No	No	No
ideograph	Yes	No	No	No

As nouns, ideograph is a hypernym of emoji; that is, ideograph is a word with a broader meaning than emoji:

emoji: ideograms and smileys used in electronic messages and Web pages
ideograph: a graphic character that indicates the meaning of a thing without indicating the sounds used to say it

Other hypernyms of emoji include ideogram.

emoji (noun)	ideograph (noun)
ideograms and smileys used in electronic messages and Web pages	a graphic character that indicates the meaning of a thing without indicating the sounds used to say it