sandhi / sandy 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. 👇
sandhi: (noun) the articulatory process whereby the pronunciation of a word or morpheme changes when it is followed immediately by another (especially in fluent speech).
sandy: NA
sandhi: NA
sandy: s·AE·n·d·iy
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)