The words tenner, tenor sound the same but have different meanings and spellings. Why do tenner, tenor sound the same even though they are completely different words?
The answer is simple: tenner, tenor are homophones of the English language.
Informal A ten-dollar bill.
Chiefly British A ten-pound note.
A continuous, unwavering course. See Synonyms at tendency.
The word, phrase, or subject with which the vehicle of a metaphor is identified, as life in "Life's but a walking shadow” ( Shakespeare).
The course of thought or argument running through something written or spoken.
General sense; purport.
Definitions 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.