plantar / planter 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. 👇
plantar: (adjective) relating to or occurring on the undersurface of the foot.
planter: (noun) the owner or manager of a plantation. (noun) a worker who puts or sets seeds or seedlings into the ground. (noun) a decorative pot for house plants.
plantar: NA
planter: p·l·AE·n·t·er
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)