The words settlors, settlers sound the same but have different meanings and spellings. Why do settlors, settlers sound the same even though they are completely different words?
The answer is simple: settlors, settlers are homophones of the English language.
Plural form of settler.
Plural form of settlor.
Definitions 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.