settler / settlor are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
settler: (noun) a person who settles in a new colony or moves into new country. (noun) a negotiator who settles disputes. (noun) a clerk in a betting shop who calculates the winnings.
settlor: (noun) (law) a person who creates a trust by giving real or personal property in trust to a trustee for the benefit of a beneficiary; a person who gives such property is said to settle it on the trustee.
settler: s·EH·t·ah·l·er
settlor: NA
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)