convulsion vs flutter

convulsion and flutter both are nouns.

Word	Noun	Adjective	Verb	Adverb
convulsion	Yes	No	No	No
flutter	Yes	No	Yes	No

As nouns, flutter is a hypernym of convulsion; that is, flutter is a word with a broader meaning than convulsion:

Other hypernyms of convulsion include commotion, disruption, disturbance, hoo-ha, hoo-hah, hurly burly, kerfuffle, to-do.

convulsion (noun)	flutter (noun)
a physical disturbance such as an earthquake or upheaval	the act of moving back and forth
violent uncontrollable contractions of muscles	the motion made by flapping up and down
a sudden uncontrollable attack	abnormally rapid beating of the auricles of the heart (especially in a regular rhythm); can result in heart block
a violent disturbance	a disorderly outburst or tumult

convulsion (verb)	flutter (verb)
	wink briefly
	beat rapidly
	move back and forth very rapidly
	move along rapidly and lightly; skim or dart
	flap the wings rapidly or fly with flapping movements