The logical data model provides a picture of all the pieces of information necessary to understand your data and how it relates to your business. It is a graphic-intensive technique that results in a data model representing the definition, characteristics, and relationships of data in a business, technical, or conceptual environment.
The physical warehouse schema is based on the logical data model, such as Day, Item, Store, or Account. Several physical warehouse schemas can be derived from the same logical data model. While the logical data model tells you what facts and attributes to create, the physical warehouse schema tells you where the underlying data for those objects is stored. The physical warehouse schema describes how your data is stored in the data warehouse.