toon / tune 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. 👇
toon: NA
tune: (noun) a succession of notes forming a distinctive sequence. (noun) the property of producing accurately a note of a given pitch. (noun) the adjustment of a radio receiver or other circuit to a required frequency. (verb) adjust for (better) functioning. (verb) adjust the pitches of (musical instruments).
toon: t·UW·n
tune: t·UW·n
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)