The words eerie, Erie sound the same but have different meanings and spellings. Why do eerie, Erie sound the same even though they are completely different words?
The answer is simple: eerie, Erie are homophones of the English language.
Inspiring inexplicable fear, dread, or uneasiness; strange and frightening.
Suggestive of the supernatural; mysterious. See Synonyms at weird.
Scots Frightened or intimidated by superstition.
A Native American people formerly inhabiting the southern shore of Lake Erie in northern Ohio, northwest Pennsylvania, and western New York. The Erie ceased to exist as a people after being defeated by the Iroquois in the mid-17th century.
A member of this people.
The Iroquoian language of the Erie.
A city of northwest Pennsylvania on Lake Erie southwest of Buffalo, New York. A port of entry, it was laid out in 1795 on the site of Fort Presque Isle, built by the French in 1753. Population: 102,000.
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").