What is the difference between an Org VDC network and vApp network?
Org VDC network - a network that is accessible to all users of the virtual data center. It can be selected for all new vApp and virtual machines in the virtual data center. You can create an isolated (without internet access) or routed network (with internet access).
vApp network – an isolated network for a single vApp. In this case, it will be accessible only to virtual machines hosted in the vApp.