SketchUp with Google Earth and the 3D Warehouse.
3D Buildings layer:
The 3D Buildings layer in Google Earth contains 3D models which you can view in Google Earth. To activate the 3D Buildings layer, make sure its checkbox is selected in the Layers area, in the lower-left corner of the Google Earth application window. Models which appear in the 3D Buildings layer are a combination of user-contributed content and content which Google has added automatically. The contents of this layer are visible to anyone who uses Google Earth. This Knowledge Center article provides information on submitting your models for inclusion in the 3D Buildings layer in Google Earth.
The term "geo-reference" is short for "geographically referenced". Models which have been geo-referenced "know" where on the planet they belong. A geo-referenced model includes information about its size, position and orientation in Google Earth. You can geo-reference a model by using SketchUp and Google Earth together. This Knowledge Center article provides information on building geo-referenced models.
A geo-located model is the same as a "geo-referenced" one; please see above for more information.
All SketchUp models are composed of surfaces. These surfaces are also called "polygons". The number of polygons in a model directly affects how well it can be viewed in Google Earth. Models with large numbers of polygons can cause Google Earth to behave sluggishly. Models with low numbers of polygons are more efficient, and are more easily viewed in Google Earth. Keeping your models' polygon count low is the best way to ensure that they look and perform will in Google Earth.
A photo-textured model is one that has been "painted" with photographs of the object represented by the model. To photo-texture a model of a building, you take photographs of that building and map them onto their corresponding surfaces using SketchUp.
When you upload your SketchUp model to the 3D Warehouse, a static view of your model is uploaded, too. That static view is called a screenshot. Your model's screenshot is generated from the view of your model that was visible in your modeling window when you uploaded it to the 3D Warehouse.