Many people might consider them similar, but I do think there is a subtle difference. Sparkling implies multiple little flashes of light, while a glint can be a single flash of light, or a brief indication, as in "I was about to abandon the search for my lost ring last night when I saw a glint of reflected light out of the corner of my eye." Hope that's helpful!

The meanings are similar, but "glint" isn't used as frequently as "sparkle."