The words unreal, unreel sound the same but have different meanings and spellings. Why do unreal, unreel sound the same even though they are completely different words?
The answer is simple: unreal, unreel are homophones of the English language.
Not real or substantial; illusory.
Slang So remarkable as to elicit disbelief; fantastic.
To unwind (something) from or as if from a reel or become unwound.
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.