poisoning vs putting to death

poisoning and putting to death both are nouns.

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

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

poisoning: the act of giving poison to a person or animal with the intent to kill
putting to death: the act of terminating a life

Other hypernyms of poisoning include kill, killing.

poisoning (noun)	putting to death (noun)
the act of giving poison to a person or animal with the intent to kill	the act of terminating a life
the physiological state produced by a poison or other toxic substance