Alto and soprano are two different terms that are well used when it comes to music term. However, the soprano is known to be the highest range of note that can ever be reached by anybody, and this range is usually produced by female voices. The soprano is a quite powerful voice that is mostly more of head voice, and kind of weak as mid voice.
The soprano voice is kind of harder to sustain, and are often taken by fewer singers in opera music. Soprano can also be characterized by musical instruments, of which the soprano sax is a typical example. Some soprano singers include Celine Dion, Mariah Carey, and Christina Aguilera, among others. There is nothing much about alto when compared to the soprano. Alto is actually considered as the deepest voice that females produced. It is also considered as a mid-voice between tenor and mezzo-soprano. The alto range is usually between G3 and F5. The popular alto singers include Toni Braxton, Brandy, Cher Lloyd, among others.