The words naval, navel sound the same but have different meanings and spellings. Why do naval, navel sound the same even though they are completely different words?
The answer is simple: naval, navel are homophones of the English language.
Of or relating to ships or shipping. See Synonyms at nautical.
Of or relating to a navy.
Having a navy: a great naval power.
The mark on the surface of the abdomen of mammals where the umbilical cord was attached during gestation. Also called umbilicus.
A central point; a middle.
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").