Lateral Movement is not only about finding additional hosts, but find some services, application, useres AND hosts for a way to privesc.

Pivoting is about using some other host as a proxy to move further in internal network.

Tunneling is a part of Pivoting, but here we are using some other protocol to encapsulate, smuggle our traffic into network for example to bypass EDR or for OPSEC. As example to use HTTP for our c2 server.

Port-Forwarding is part of Pivoting, but here we are using a ssh protocol (mostly) to port forward some our local port to victim's port.