ejaculation vs expelling

ejaculation and expelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
ejaculation	Yes	No	No	No
expelling	Yes	No	No	No

As nouns, expelling is a hypernym of ejaculation; that is, expelling is a word with a broader meaning than ejaculation:

ejaculation: the discharge of semen in males
expelling: any of several bodily processes by which substances go out of the body

Other hypernyms of ejaculation include discharge, emission.

ejaculation (noun)	expelling (noun)
an abrupt emphatic exclamation expressing emotion	any of several bodily processes by which substances go out of the body
the discharge of semen in males