The words pidgin, pigeon sound the same but have different meanings and spellings. Why do pidgin, pigeon sound the same even though they are completely different words?
The answer is simple: pidgin, pigeon are homophones of the English language.
A simplified form of speech that is usually a mixture of two or more languages, has a rudimentary grammar and vocabulary, is used for communication between groups speaking different languages, and is not spoken as a first or native language. Also called contact language.
Any of various birds of the widely distributed family Columbidae, characteristically having plump bodies, small heads, and short legs, especially the rock dove or any of its domesticated varieties.
Slang One who is easily swindled; a dupe.
An object of special concern; an affair or matter.
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").