mare / mayor 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. 👇
mare: (noun) female equine animal. (noun) a dark region of considerable extent on the surface of the moon.
mayor: (noun) the head of a city government.
mare: m·EH·r
mayor: m·EY·er
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)