The words flay, fley sound the same but have different meanings and spellings. Why do flay, fley sound the same even though they are completely different words?
The answer is simple: flay, fley are homophones of the English language.
To strip off the skin or outer covering of.
To strip of money or goods; fleece.
To whip or lash.
To assail with stinging criticism; excoriate.
Scots To frighten.
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.