blurt out vs speak

blurt out and speak both are verbs.

Word	Noun	Adjective	Verb	Adverb
blurt out	No	No	Yes	No
speak	No	No	Yes	No

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

Other hypernyms of blurt out include mouth, talk, utter, verbalise, verbalize.

blurt out (verb)	speak (verb)
utter impulsively	express in speech
	exchange thoughts; talk with
	use language
	give a speech to
	make a characteristic or natural sound