preliminary vs inception

preliminary and inception both are nouns.

Word	Noun	Adjective	Verb	Adverb
preliminary	Yes	Yes	No	No
inception	Yes	No	No	No

As nouns, inception is a hypernym of preliminary; that is, inception is a word with a broader meaning than preliminary:

preliminary: something that serves as a preceding event or introduces what follows
inception: an event that is a beginning; a first part or stage of subsequent events

Other hypernyms of preliminary include origin, origination.

preliminary (noun)	inception (noun)
a minor match preceding the main event	an event that is a beginning; a first part or stage of subsequent events
something that serves as a preceding event or introduces what follows

preliminary (adjective)	inception (adjective)
denoting an action or event preceding or in preparation for something more important