Resource Sharing Mode disabled by default. This means that each user of an account will see his own resources. For example, user 1 creates a VM called "SQL" and user 2 creates a VM called "webserver", user 2 cannot see "SQL" and user 1 cannot see "webserver". If resource sharing mode is enabled, all users in an account share the resources used and the VMs created. The second option is used for customers who act as managed service providers and manage the environment for their customers to some extent. They could have a service user in the customer account which has access to all resources and simultaneously the customer can have users who views the same resources.