titty vs sideboob

titty and sideboob both are nouns.

Word	Noun	Adjective	Verb	Adverb
titty	Yes	No	No	No
sideboob	Yes	No	No	No

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

titty: either of two soft fleshy milk-secreting glandular organs on the chest of a woman
sideboob: A breast exposed from the side

titty (noun)	sideboob (noun)
either of two soft fleshy milk-secreting glandular organs on the chest of a woman	A breast exposed from the side