Different martial arts, same kind of principles

In fact sometimes I feel that as a judo practitioner, many of the martial arts principles are kind of the same. It is all about the body movements and the differences are the techniques used by each martial arts. Like judo, it has more emphasis on the throws and grappling. For Taekwondo, it is more on the legs. But sometimes in the self defense aspect of Taekwondo, there are also throws and these throws will have the same principles as those found in judo. Therefore principles can be seen from here that they are overlapped with one another.