The words dean, dene sound the same but have different meanings and spellings. Why do dean, dene sound the same even though they are completely different words?
The answer is simple: dean, dene are homophones of the English language.
An administrative officer in charge of a college, faculty, or division in a university.
An officer of a college or high school who counsels students and supervises the enforcement of rules.
Ecclesiastical The head of the chapter of canons governing a cathedral or collegiate church.
Roman Catholic Church A priest appointed to oversee a group of parishes within a diocese.
Chiefly British A sandy tract or dune by the seashore.
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.