Oh the confusion 😉 These beauty terms are sometimes a lot to take in so let’s make it simple;
Shellac (the brand name for a nail product created by Creative Nail Design (CND) is a mix of nail polish and gel and the main difference is that, unlike acrylics and gel, shellac cannot extend the nail as it’s basically a polish, but it does add strength and is less damaging than acrylics/gel. Shellac should last for up to 2 weeks and gives a beautiful glossy look. Then you also have Gelish (by NailHarmony) which is pretty much the same as Shellac but is said to last up to 3 weeks. I’d say that it’s all depending on a persons lifestyle and how you treat your nails and therefore I leave them in the same category. So to sum up: Gelish and Shellac do not extend or re-shape the nails but gives a glossy, beautiful result lasting for 2-3 weeks.
So, if you want longer nails and/or a different shape, what you want is acrylics or gel, which is totally different and something you add on top of your natural nail (basically like adding a fake nail) These options are in my opinion quite damaging and you often end up with weaker nails. Acrylics are probably the worst option when it comes to ruining the nail bed and they tend to look more fake than gels, but they are very strong and long-lasting. Gels are also damaging if done too frequently but provides a glossy and natural look.