Well, the ingredients and distilling processes are different. You can make Vodka from more or less anything - wheat, rice, corn, barley, rye, sorghum, grapes… the list goes on.
Whether it’s made from grains or potatoes, once it’s all been mashed up, it’s the enzymes that get to work and create the fermentation and sugars needed for it to become Vodka.
Multiple distillations, filtration, and search for the purest water to use in Vodka’ contribute to the neutral character of the “little water.” Usually, Vodka has an alcohol content of 40-55% and is less flavorful than other Spirits - which is why some don’t care for it, and for others, it’s their go-to cocktail buddy.