saccharin / saccharine 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. 👇
saccharin: (noun) a crystalline substance 500 times sweeter than sugar; used as a calorie-free sweetener.
saccharine: NA
saccharin: s·AE·k·er·ah·n
saccharine: s·AE·k·er·AY·n
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)