The words news, gnus sound the same but have different meanings and spellings. Why do news, gnus sound the same even though they are completely different words?
The answer is simple: news, gnus are homophones of the English language.
Plural form of gnu.
Information about recent events or happenings, especially as reported by newspapers, periodicals, radio, or television.
A presentation of such information, as in a newspaper or on a newscast.
New information of any kind: The requirement was news to him.
Newsworthy material: "a public figure on a scale unimaginable in America; whatever he did was news” ( James Atlas).
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License, from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").