Network of evolutionary trends (NET)
It is a network describing the historical evolution of a given technical system, as well as its potential directions for further development. The nodes of such network are the different states in which the technical system has been, is or could be in the future. The links of the networks are trends that drive the transition from a generation to another.
Evolutionary tree (or Phylogenetic tree)
It is a concept derived from biology, where it shows the relationships among living species in hierarchical terms. The branches of the tree describe the pattern of evolution (from less evolved – ancestors- to more evolved species – offsprings). The same logic can be applied for describing the evolution of technical systems.