insight vs breakthrough

insight and breakthrough both are nouns.

Word	Noun	Adjective	Verb	Adverb
insight	Yes	No	No	No
breakthrough	Yes	No	No	No

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

Other hyponyms of insight include light, revelation, discovery, find, flash.

insight (noun)	breakthrough (noun)
grasping the inner nature of things intuitively	a penetration of a barrier such as an enemy's defense
the clear (and often sudden) understanding of a complex situation	making an important discovery
clear or deep perception of a situation	a productive insight
a feeling of understanding