significance vs lesson

significance and lesson both are nouns.

Word	Noun	Adjective	Verb	Adverb
significance	Yes	No	No	No
lesson	Yes	No	No	No

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

significance (noun)	lesson (noun)
the quality of being significant	a task assigned for individual study
a meaning that is not expressly stated but can be inferred	a unit of instruction
the message that is intended or expressed or signified	punishment intended as a warning to others
	the significance of a story or event