nucleolar organizer vs nucleolus organizer

nucleolar organizer and nucleolus organizer both are nouns.

Word	Noun	Adjective	Verb	Adverb
nucleolar organizer	Yes	No	No	No
nucleolus organizer	Yes	No	No	No

As nouns, nucleolar organizer and nucleolus organizer are synonyms defined as:

nucleolar organizer and nucleolus organizer: the particular part of a chromosome that is associated with a nucleolus after nuclear division

Other synonyms of nucleolar organizer include nucleolar organiser, nucleolus organiser.

nucleolar organizer (noun)	nucleolus organizer (noun)
the particular part of a chromosome that is associated with a nucleolus after nuclear division	the particular part of a chromosome that is associated with a nucleolus after nuclear division