Hook up and Plug-in

Hook up verb - To come or be together as friends.

Plug-in and hook up are semantically related. In some cases you can replace phrase "Plug-in" with "Hook up", this terms are similar.

Plug-in noun - A printed circuit that can be inserted into expansion slots in a computer to increase the computer's capabilities.

Hook up and plug-in are semantically related. Sometimes you can use "Hook up" instead a verb phrase "Plug-in".