text vs speech balloon

text and speech balloon both are nouns.

Word	Noun	Adjective	Verb	Adverb
text	Yes	No	Yes	No
speech balloon	Yes	No	No	No

As nouns, speech balloon is a hyponym of text; that is, speech balloon is a word with a more specific, narrower meaning than text:

text (noun)	speech balloon (noun)
the words of something written	in cartooning, a rounded outline containing words.
the main body of a written work (as distinct from illustrations or footnotes etc.)
a book prepared for use in schools or colleges
a passage from the Bible that is used as the subject of a sermon

text (verb)	speech balloon (verb)
to send a message by SMS or similar text-based messaging service