The words ail, ale sound the same but have different meanings and spellings. Why do ail, ale sound the same even though they are completely different words?
The answer is simple: ail, ale are homophones of the English language.
To feel ill or have pain.
To cause physical or mental pain or uneasiness to; trouble. See Synonyms at trouble.
A fermented alcoholic beverage containing malt and hops, similar to but heavier than beer.
A serving of this beverage.
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").