What is the difference between a Full License and a Network Device

In a nutshell, full licenses are intended to be used for Windows(R) servers and workstations, whereas network device licenses are intended to be used for Non-Windows devices like switches, routers, Linux/Unix hosts and other IP-based network devices.

Full Licenses
Can be used on any supported Windows(R) operating system. A single full license allows you to monitor as many metrics as you would like on a licensed hosts, there are no other limits in regards to how much log data can be collected, how many performance counters can be configured and so forth.

Network Device Licenses
Can be used on any IP-based network device except for hosts running the Windows(R) operating system (which require a full license). A single network device license allows you to monitor as many metrics as you would like on a licensed hosts, there are no other limits in regards to how much Syslog data can be collected, how many SNMP counters can be configured and so forth.

Network device monitoring supports the following:

Availability Monitoring through ping
TCP port checks
Syslog messages
SNMP-capable devices: SNMP traps
SNMP-capable devices: System information, active network devices
SNMP-capable devices: Monitor disk space, running processes and SNMP counters (no limit).
SSH-capable devices: Monitor daemons (services)