upheaval vs to-do

upheaval and to-do both are nouns.

Word	Noun	Adjective	Verb	Adverb
upheaval	Yes	No	No	No
to-do	Yes	No	No	No

As nouns, to-do is a hypernym of upheaval; that is, to-do is a word with a broader meaning than upheaval:

Other hypernyms of upheaval include commotion, disruption, disturbance, flutter, hoo-ha, hoo-hah, hurly burly, kerfuffle.

upheaval (noun)	to-do (noun)
disturbance usually in protest	a disorderly outburst or tumult
(geology) a rise of land to a higher elevation (as in the process of mountain building)
a state of violent disturbance and disorder (as in politics or social conditions generally)
a violent disturbance