The words may be, maybe (2 words/1 word) sound the same but have different meanings and spellings. Why do may be, maybe (2 words/1 word) sound the same even though they are completely different words?
The answer is simple: may be, maybe (2 words/1 word) are homophones of the English language.
Common misspelling of maybe.
Informal An uncertainty: There are so many maybes involved in playing the stock market.
Informal An uncertain reply: It's better to receive a fast and honest no than a drawn-out maybe.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License, 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").