sensitizing vs immunization

sensitizing and immunization both are nouns.

Word	Noun	Adjective	Verb	Adverb
sensitizing	Yes	Yes	No	No
immunization	Yes	No	No	No

As nouns, immunization is a hypernym of sensitizing; that is, immunization is a word with a broader meaning than sensitizing:

sensitizing: rendering an organism sensitive to a serum by a series of injections
immunization: the act of making immune (especially by inoculation)

Other hypernyms of sensitizing include immunisation.

sensitizing (noun)	immunization (noun)
rendering an organism sensitive to a serum by a series of injections	the act of making immune (especially by inoculation)

sensitizing (adjective)	immunization (adjective)
making susceptible or sensitive to either physical or emotional stimuli