trainee vs initiate

trainee and initiate both are nouns.

Word	Noun	Adjective	Verb	Adverb
trainee	Yes	No	No	No
initiate	Yes	No	Yes	No

As nouns, initiate is a hypernym of trainee; that is, initiate is a word with a broader meaning than trainee:

Other hypernyms of trainee include beginner, novice, tiro, tyro.

trainee (noun)	initiate (noun)
someone who is being trained	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

trainee (verb)	initiate (verb)
	set in motion, start an event or prepare the way for
	bring up a topic for discussion
	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