An application is the service or series of services that you are going to deploy to fulfill a definite purpose or series of purposes. For example, a banking application allows you to perform multiple different actions like checking your account balance, transferring funds between accounts, and so on.
The difference between an application and a service is subtle as Spinnaker does not natively distinguish between the two. However, to clarify, an application can consist of many different services and represents the overall product you are trying to deploy, while a service is more so the individual features of that product you are trying to deploy. This distinction allows you to manage applications.
After your successful login to your ISD application, the application dashboard is displayed as shown below. The list of created applications or applications to which you have the relevant permissions is displayed.
ISD provides the capability to create new ISD applications and modify the existing applications. Applications shown in the above figure depicts the name of the application that you have created and have access.