The words ar, are sound the same but have different meanings and spellings. Why do ar, are sound the same even though they are completely different words?
The answer is simple: ar, are are homophones of the English language.
Variant of are2.
The letter r.
Second person singular and plural and first and third person plural present indicative of be.
A metric unit of area equal to 100 square meters (119.6 square yards).
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.