From this post What's the difference between streams and datagrams in network programming?, the 2nd answer says:
Stream Socket:
Dedicated & point-to-point channel between server and client.
...
Datagram Socket:
No dedicated & point-to-point channel between server and client.
...
What is the point-to-point channel described here ? Why stream socket is point to point while datagram is not?
A stream socket provides a connection between two endpoints. Point to point channel means usually a TCP connection. A connection is established before user data is sent and the connection is released later. The connection has always two end points and data can be transferred between these end points.
A datagram socket can be used for communication with multiple peers. It is usually used for communication over UDP. A datagram socket is not bound to any remote peer and it is possible to receive data from multiple peers through a single datagram socket. It is even possible to send data to multiple peers through a datagram socket when destination address is a broadcast or multicast address.
