euthanasia vs putting to death

euthanasia and putting to death both are nouns.

Word	Noun	Adjective	Verb	Adverb
euthanasia	Yes	No	No	No
putting to death	Yes	No	No	No

As nouns, putting to death is a hypernym of euthanasia; that is, putting to death is a word with a broader meaning than euthanasia:

euthanasia: the act of killing someone painlessly (especially someone suffering from an incurable illness)
putting to death: the act of terminating a life

Other hypernyms of euthanasia include kill, killing.

euthanasia (noun)	putting to death (noun)
the act of killing someone painlessly (especially someone suffering from an incurable illness)	the act of terminating a life