The words form, forme sound the same but have different meanings and spellings. Why do form, forme sound the same even though they are completely different words?
The answer is simple: form, forme are homophones of the English language.
A linguistic form.
The shape and structure of an object.
The body or outward appearance of a person or an animal considered separately from the face or head; figure.
The essence of something.
An arrangement of metal or wood type, from which a page may be printed
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition, from Wiktionary, Creative Commons Attribution/Share-Alike License 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").