Frames are full layouts. Themes change colors. Frames change everything: how your avatar sits, how links stack, whether there is a hero image, the typography.
Open the dashboard, click Frames, browse, click one to preview live in the main panel.
Switching frames
Pick a different one and the preview updates. To go back to the default list view, pick "None" in the Frames panel.
Why some frames hide certain blocks
Some frames are built around a single hero link or a specific layout. If your spotlight or audience block does not appear, the frame probably does not include that slot. The data is still saved.