The words muscat, musket sound the same but have different meanings and spellings. Why do muscat, musket sound the same even though they are completely different words?
The answer is simple: muscat, musket are homophones of the English language.
Any of various sweet white grapes used for making wine or raisins.
A smoothbore shoulder gun used from the late 16th through the 18th century.
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.
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").