The GenericSNMPTrapAgent and the TrapAgent are used for different purposes.
The GenericSNMPTrapAgent is provided with the SNMP cartridge. The GenericSNMPTrapAgent is used to receive traps from servers that are monitored by the GenericSNMP* agents. If the server is not monitored by the GenericSNMP* agents, then the traps from the server are discarded.
The TrapAgent is provided with the Integration cartridge to allow alarms to be generated for devices that aren't monitored by Foglight agents. The TrapAgent receives traps sent by devices. The TrapAgent does not poll for data.