A gel manicure and a Shellac manicure are essentially the same thing: long-lasting polishes cured under UV lamps. The difference is that “gel nails” or “manicure” is the generic term for any nails done under a UV lamp which includes shellac, whilst Shellac itself a brand of gel nails by the company Creative Nail Design (CND). It’s comparable to “Henry Hoover” which was so popular that people often call a vacuum cleaner a “Hoover”.