We're looking at 3 different usage metrics.
Network Device, Network Active, and Licensed Device are all different things.
The only way to reliably get the Managed Devices (Licensed Devices) on a system is to run the "Managed Devices" report.
This will give you an exact count of your managed devices, and list the devices as well.
As a general rule, if NetMRI cannot SNMP poll the device, or if SNMP is disabled (via NetMRI) for a device, the device is not a managed device.