Terminology
Webpage Builder: When Page Builder is initiated from Pages -> Page Builder
Homepage Builder: When Page Builder is initiated from Customer Sites -> Page Builder
Editor: The entire interface of Page Builder, containing Panels and the Canvas
Panels: The horizontal bar in the header and the vertical column on the right. Comprises Settings and Actions for the Editor, as well as additional settings for Components within the Canvas
Canvas: Where you drag/drop Blocks to create Components
Blocks: Reusable pieces of HTML/CSS that you drag/drop into the canvas
Components: Each element within the canvas