ray / re 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. 👇
ray: (noun) a branch of an umbel or an umbelliform inflorescence. (noun) (mathematics) a straight line extending from a point. (noun) any of the stiff bony spines in the fin of a fish. (noun) cartilaginous fishes having horizontally flattened bodies and enlarged winglike pectoral fins with gills on the underside; most swim by moving the pectoral fins. (verb) emit as rays.
re: (noun) the syllable naming the second (supertonic) note of any major scale in solmization.
ray: r·EY
re: r·EY
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)