undertake vs hire

undertake is not a noun while hire is a noun.

Word	Noun	Adjective	Verb	Adverb
undertake	No	No	Yes	No
hire	Yes	No	Yes	No

As verbs, hire is a hyponym of undertake; that is, hire is a word with a more specific, narrower meaning than undertake:

Other hyponyms of undertake include stipulate, sign, condition, qualify, specify, stipulate, lease, rent, charter, lease, rent.

undertake (noun)	hire (noun)
	the act of hiring something or someone
	a newly hired employee

undertake (verb)	hire (verb)
promise to do or accomplish	engage for service under a term of contract
enter into a contractual arrangement	engage or hire for work
enter upon an activity or enterprise	hold under a lease or rental agreement; of goods and services
accept as a charge
accept as a challenge