gemination vs repetition

gemination and repetition both are nouns.

Word	Noun	Adjective	Verb	Adverb
gemination	Yes	No	No	No
repetition	Yes	No	No	No

As nouns, repetition is a hypernym of gemination; that is, repetition is a word with a broader meaning than gemination:

gemination: the doubling of a word or phrase (as for rhetorical effect)
repetition: the repeated use of the same word or word pattern as a rhetorical device

gemination (noun)	repetition (noun)
the act of copying or making a duplicate (or duplicates) of something	the act of doing or performing again
the doubling of a word or phrase (as for rhetorical effect)	the repeated use of the same word or word pattern as a rhetorical device
	an event that repeats