The words moose, mousse sound the same but have different meanings and spellings. Why do moose, mousse sound the same even though they are completely different words?
The answer is simple: moose, mousse are homophones of the English language.
A hoofed mammal (Alces alces) found in forests of northern North America and in Eurasia and having a broad, pendulous muzzle and large, palmate antlers in the male.
Any of various chilled desserts made with flavored whipped cream, gelatin, and eggs: chocolate mousse.
A molded dish containing meat, fish, or shellfish combined with whipped cream and gelatin.
An aerosol foam used to control and style the hair.
To apply a styling foam to (the hair).
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.