The words quean, queen sound the same but have different meanings and spellings. Why do quean, queen sound the same even though they are completely different words?
The answer is simple: quean, queen are homophones of the English language.
A woman regarded as being disreputable, especially a prostitute.
Scots A young woman.
The wife or widow of a king.
A woman sovereign.
Something having eminence or supremacy in a given domain and personified as a woman: Paris is regarded as the queen of cities.
Games The most powerful chess piece, able to move in any direction over any number of empty squares in a straight line.
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").