I guess part form the ingedients and the process, Jack Daniels has a more "smooth" taste. You can best taste the difference when you drink it "pure'. No ice and no coke.
To be honost, Jack Daniels has a lot of different types of whiskey. The common black label differs a lot from for example the Silver Select, Monogram, Gentleman Jack or Master distiller. Al these have also their own typical taste.
Just try and you will find out.