The words sandhi, sandy sound the same but have different meanings and spellings. Why do sandhi, sandy sound the same even though they are completely different words?
The answer is simple: sandhi, sandy are homophones of the English language.
Modification of the sound of a word or morpheme when juxtaposed with another, especially in fluent speech, as the modification of the pronunciation of don't in don't you from its pronunciation in isolation or in a phrase like don't we.
Covered with, full of, or consisting of sand.
Having characteristics similar to sand.
Of the color of sand; light yellowish brown.
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.