intonation vs singsong

intonation and singsong both are nouns.

Word	Noun	Adjective	Verb	Adverb
intonation	Yes	No	No	No
singsong	Yes	Yes	Yes	No

As nouns, singsong is a hyponym of intonation; that is, singsong is a word with a more specific, narrower meaning than intonation:

Other hyponyms of intonation include intonation pattern, drone, droning, monotone.

intonation (noun)	singsong (noun)
the act of singing in a monotonous tone	informal group singing of popular songs
singing by a soloist of the opening piece of plainsong	a regular and monotonous rising and falling intonation
the production of musical tones (by voice or instrument); especially the exactitude of the pitch relations
rise and fall of the voice pitch

intonation (adjective)	singsong (adjective)
	uttered in a monotonous cadence or rhythm as in chanting

intonation (verb)	singsong (verb)
	speak, chant, or declaim in a singsong
	move as if accompanied by a singsong