POL & POM Terminology
A virtual drive is simply the name that PlayOnLinux/PlayOnMac uses for a Wine WINEPREFIX, which is essentially a self-contained Wine environment, complete with it's own drive_c folders and everything else. For more information on what a WINEPREFIX is, read here.
A "component" is a dependency, library, set of DLL's, etc., that Wine may need to use to get a program to run. The Install Components menu has similar functionality to other apps/scripts like winetricks. If you are looking for a dependency from winetricks, you will likely find it in the Install Components menu.
A function or installer for PlayOnLinux/PlayOnMac. When you install a game or application from the Install" menu, a script is downloaded and ran, which guides you through the installation process. During installation, the script automatically uses others scripts to interact with our server and PlayOnLinux's API to gather everything needed to create a Virtual Drive to house your game or app.