Both pipes and sockets handle byte streams, but they do it in different ways…
pipes only exist within a specific host, and they refer to buffering between virtual files, or connecting the output / input of processes within that host. There are no concepts of packets within pipes.
sockets packetize communication using IPv4 or IPv6; that communication can extend beyond localhost. Note that different endpoints of a socket can share the same IP address; however, they must listen on different TCP / UDP ports to do so.
Usage:
Use pipes:when you want to read / write data as a file within a specific server. If you’re using C, you read() and write() to a pipe.
when you want to connect the output of one process to the input of another process… see popen()
Use sockets to send data between different IPv4 / IPv6 endpoints. Very often, this happens between different hosts, but sockets could be used within the same host
BTW, you can use netcat or socat to join a socket to a pipe.