mandrel / mandrill 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. 👇
mandrel: NA
mandrill: (noun) baboon of west Africa with a bright red and blue muzzle and blue hindquarters.
mandrel: NA
mandrill: m·AE·n·d·r·ih·l
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)