better / bettor 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. 👇
better: (noun) something superior in quality or condition or effect. (noun) a superior person having claim to precedence. (noun) the superior one of two alternatives. (verb) surpass in excellence. (verb) to make better. (verb) get better. (adjective) (comparative of `good') superior to another (of the same class or set or kind) in excellence or quality or desirability or suitability; more highly skilled than another. (adjective) (comparative of `good') changed for the better in health or fitness. (adjective) (comparative and superlative of `well') wiser or more advantageous and hence advisable. (adjective) more than half. (adverb) comparative of `well'; in a better or more excellent manner or more advantageously or attractively or to a greater degree etc.. (adverb) from a position of superiority or authority.
bettor: (noun) someone who bets.
better: b·EH·t·er
bettor: b·EH·t·er
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)