initiate vs strike up

initiate is a noun but strike up is not a noun.

Word	Noun	Adjective	Verb	Adverb
initiate	Yes	No	Yes	No
strike up	No	No	Yes	No

As verbs, strike up is a hyponym of initiate; that is, strike up is a word with a more specific, narrower meaning than initiate:

initiate (noun)	strike up (noun)
people who have been introduced to the mysteries of some field or activity
someone who has been admitted to membership in a scholarly field
someone new to a field or activity

initiate (verb)	strike up (verb)
set in motion, start an event or prepare the way for	begin
bring up a topic for discussion	start playing
take the lead or initiative in; participate in the development of
bring into being
accept people into an exclusive society or group, usually with some rite