EtherNet/IP is the implementation of the CIP protocol over standard Ethernet.
The EtherNet/IP protocol uses an Originator/Target architecture for data exchange.
Originators are devices that initiate data exchanges with Target devices on the network. This applies to both I/O communications and service messaging. This is the equivalent of the role of a client in a Modbus network.
Targets are devices that respond to data requests generated by Originators. This applies to both I/O communications and service messaging. This is the equivalent of the role of a server in a Modbus network.
EtherNet/IP Adapter is an end-device in an EtherNet/IP network. I/O blocks and drives can be EtherNet/IP Adapter devices.
The communication between an EtherNet/IP Originator and Target is accomplished using an EtherNet/IP connection.