lullaby vs song

lullaby and song both are nouns.

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

As nouns, song is a hypernym of lullaby; that is, song is a word with a broader meaning than lullaby:

Other hypernyms of lullaby include strain.

As nouns, song is a hypernym of lullaby; that is, song is a word with a broader meaning than lullaby:

Other hypernyms of lullaby include vocal.

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