news vs write up

news and write up both are nouns.

Word	Noun	Adjective	Verb	Adverb
news	Yes	No	No	No
write up	Yes	No	Yes	No

As nouns, write up is a hyponym of news; that is, write up is a word with a more specific, narrower meaning than news:

news (noun)	write up (noun)
the quality of being sufficiently interesting to be reported in news bulletins	a short account of the news
information about recent and important events
information reported in a newspaper or news magazine
a program devoted to current events, often using interviews and commentary
informal information of any kind that is not previously known to someone

news (verb)	write up (verb)
	bring to public notice by writing, with praise or condemnation
	put into writing; write in complete form