rancor / ranker 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. 👇
rancor: NA
ranker: (noun) a commissioned officer who has been promoted from enlisted status. (noun) an enlisted soldier who serves in the ranks of the armed forces.
rancor: r·AE·ng·k·er
ranker: r·AE·ng·k·er
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)