The words stater, stator sound the same but have different meanings and spellings. Why do stater, stator sound the same even though they are completely different words?
The answer is simple: stater, stator are homophones of the English language.
A resident of a particular state or type of state. Often used in combination: Lone Star staters; farm staters; the struggle between slave staters and free staters.
Any of various gold, silver, or electrum coins of ancient Greece.
The stationary part of a motor, dynamo, turbine, or other working machine about which a rotor turns.
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").