saner / seiner 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. 👇
saner: (adjective) mentally healthy; free from mental disorder.
seiner: NA
saner: s·EY·n·er
seiner: NA
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)