song vs lullaby

song and lullaby both are nouns.

Word	Noun	Adjective	Verb	Adverb
song	Yes	No	No	No
lullaby	Yes	No	No	No

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

Other hyponyms of song include carol, cradlesong.

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

song (noun)	lullaby (noun)
the act of singing	the act of singing a quiet song to lull a child to sleep
a short musical composition with words	a quiet song intended to lull a child to sleep
the characteristic sound produced by a bird
a distinctive or characteristic sound
a very small sum