sing vs speak

sing and speak both are verbs.

Word	Noun	Adjective	Verb	Adverb
sing	No	No	Yes	No
speak	No	No	Yes	No

As verbs, speak is a hypernym of sing; that is, speak is a word with a broader meaning than sing:

Other hypernyms of sing include mouth, talk, utter, verbalise, verbalize.

sing (verb)	speak (verb)
make a whining, ringing, or whistling sound	express in speech
divulge confidential information or secrets	exchange thoughts; talk with
to make melodious sounds	use language
produce tones with the voice	give a speech to
deliver by singing	make a characteristic or natural sound