The words settler, settlor sound the same but have different meanings and spellings. Why do settler, settlor sound the same even though they are completely different words?
The answer is simple: settler, settlor are homophones of the English language.
One who settles in a new region.
One who settles or decides something.
One that makes a business or financial settlement or a settlement of property.
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.