What is the difference between EtherNet/IP and TCP/IP?

Overall is very hard for them to be compared because they are not providing the same results, but a TCP/IP is a part of a protocol suite and EtherNet/IP is a communication protocol.

EtherNet/IP is a communication protocol that is implemented as Common Industrial Protocol (CIP) over the standard Ethernet. CIP's tasks are accessed by using explicit messaging over a TCP connection and Implicit messaging over a UDP connection.

On the other side, TCP/IP is just a protocol suite as a part of the OSI model and provides a lection of communication protocols that are required in order to make communication over Ethernet possible.

The most important components of the TCP/IP suite are the IP, TCP, and UDP.

IP is the Internet Protocol responsible for packet moving from point A to point B.

TCP stands for Transmission Control Protocol and it is a connection-oriented protocol, responsible for managing client-server connections, ensuring the messages reach their destination.

UPD, User Datagram Protocol is a connectionless protocol used for fast packet transmission without the need for acknowledgment or any concern if the packets arrive at the destination.