fact vs rudiments

fact and rudiments both are nouns.

Word	Noun	Adjective	Verb	Adverb
fact	Yes	No	No	No
rudiments	Yes	No	No	No

As nouns, rudiments is a hyponym of fact; that is, rudiments is a word with a more specific, narrower meaning than fact:

fact: a statement or assertion of verified information about something that is the case or has happened
rudiments: a statement of fundamental facts or principles

Other hyponyms of fact include book, record, record book, basics, index, index number, indicant, indicator.

fact (noun)	rudiments (noun)
a piece of information about circumstances that exist or events that have occurred	the elementary stages of any subject (usually plural)
a concept whose truth can be proved	a statement of fundamental facts or principles
a statement or assertion of verified information about something that is the case or has happened
an event known to have happened or something known to have existed