The words bridal, bridle sound the same but have different meanings and spellings. Why do bridal, bridle sound the same even though they are completely different words?
The answer is simple: bridal, bridle are homophones of the English language.
A marriage ceremony; a wedding.
Of or relating to a bride or a marriage ceremony; nuptial.
Designed for a bride or a newly married couple: a bridal shop; the hotel's bridal suite.
A harness, consisting of a headstall, bit, and reins, fitted about a horse's head and used to restrain or guide the animal.
A curb or check: put a bridle on spending.
Nautical A span of chain, wire, or rope that can be secured at both ends to an object and slung from its center point.
To put a bridle on.
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").