thanksgiving vs prayer

thanksgiving and prayer both are nouns.

Word	Noun	Adjective	Verb	Adverb
thanksgiving	Yes	No	No	No
prayer	Yes	No	No	No

As nouns, prayer is a hypernym of thanksgiving; that is, prayer is a word with a broader meaning than thanksgiving:

Other hypernyms of thanksgiving include orison, petition.

thanksgiving (noun)	prayer (noun)
a short prayer of thanks before a meal	the act of communicating with a deity (especially as a petition or in adoration or contrition or thanksgiving)
	earnest or urgent request
	a fixed text used in praying
	reverent petition to a deity
	someone who prays to God