From Unity to Godot: Game Objects and Components in Godot?

Coming from Unity, you just opened Godot for the first time and you can’t find where are the Game Objects and Components? Not only that, where are the Prefabs and Levels? All you can see are four buttons under a label: “Create Root Node”. What are Nodes? Where do I even add my custom scripts? How different are Godot Scenes from Unity’s Scenes (Levels)?