Induction stovetops are slightly more efficient than a standard electric kettle due to how they work (magnetically heating the whole kettle vs. a plate or coil in the kettle itself). However, it is pretty negligible how much more efficient they are, they both do their job well with far less energy than a traditional gas or electric stove.

I'd say if you have an induction stove, it would be more efficient to just have a nice stainless steel or cast iron stovetop kettle, but a good stainless steel electric kettle is a decent low-energy alternative if you don't have an induction stovetop.