A clone is an individual that is genetically identical to another (see wikipedia > cloning). As you said, identical twins (better called monozygotic twins) are genetically identical to one another and therefore an identical twin is a clone indeed. read more
Identical twins are individuals that are from the same original embryo. Clones might be from the same individual, but the genetic information contained in the nucleus, is transferred to different eggs. read more
The identical twins, in particular, are really the same with clones in the physical sense. However, there are some technicalities that differentiate the two. When a mother will give birth to two offspring, the resulting newborn babies are called twins. read more