Data warehousing encompasses a complete architecture and process, whereas Data warehouse is Data stored in Database in the form of Dimension Tables, Fact Tables, Lookup Tables, Aggregated Fact tables.
Data warehousing is not just having a single data warehouse. Data warehousing is the transformation of data to information, thereby enabling the business to examine its operations and performance. This task is accomplished by the staging and transformation of data from data sources, enabling the business to access and analyze information. The data stores may be persistent (stored on disk) or transient (using disk or memory). In addition, the workflow usually involves multiple data stores to support the staging and transformation of data into information such as operational data stores, data warehouses, data marts, online analytical processing cubes, files such as a flat file (comma-separated values extract, for example), XML data and even spreadsheets.