Syncope uses entities like connectors bundles, connector instances and external resources to synchronize user accounts with and propagate to external systems.
This page clarifies what the responsibility and scope of each of these entities are.

Connector bundle

Connector bundles are the components that are able to connect to classes of systems when configured correctly and told to do so. They are not bound to Syncope specifically, as they
are part of the separate framework ConnId, but they can be plugged into a deployed Syncope system.

Connector instance

Connectors instances are instance of connector bundles, obtained by assigning values to configuration properties defined in bundles.
For instance, there is only a single "DatabaseTable connector" (the bundle) that can be instantiated many times, for example if there is need to connect to two different databases.

External resource

Resources are meant to encapsulate all information about how Syncope will use connector instances for its own purpose (i.e. provisioning). That's why, when defining a Resource, you can define how the data provided by a certain connector are mapped to user attributes, managed by Syncope. The latter is called the schema mapping.

...