The differences between two model versions can be detected by the software tool BiVeS.  We developed a JSON schema to communicate the differences at the network level and extended BiVeS accordingly. 
BiVeS
Additionally, we developed DiVil, a web-based tool to represent the model and the differences as a standardised network using D3.  Availability and implementation: DiVil prototype: https://divil.bio.informatik.uni-rostock.de, Code on GitHub: https://github.com/Gebbi8/DiVil, licensed under Apache License 2.0. 
DiVil