news vs newscast

news and newscast both are nouns.

Word	Noun	Adjective	Verb	Adverb
news	Yes	No	No	No
newscast	Yes	No	No	No

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

news (noun)	newscast (noun)
the quality of being sufficiently interesting to be reported in news bulletins	a broadcast of news or commentary on 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