Key difference: A data warehouse is a database used to store data. It is a central repository of data in which data from various sources is stored. The data warehouse is then used for reporting and data analysis. A database, on the other hand, is the basis or any data storage. It is an organized collection of data. A database is used to store data while a data warehouse is mostly used to facilitate reporting and analysis.

A data warehouse is a database used to store data. It is a central repository of data in which data from various sources is stored. A data warehouse is also known as an enterprise data warehouse.

The data warehouse is then used for reporting and data analysis. It can be used for creating trending reports for senior management reporting such as annual and quarterly comparisons.

The purpose of a data warehouse is to provide flexible access to the data to the user. Data warehousing generally refers to the combination of many different databases across an entire enterprise. Data warehouses store current as well as historical data, so that all of the relevant data may be used for analysis. The analysis helps to find and show relationships among the data, to extract meaning from the data.

A database, on the other hand, is the basis or any data storage. It is an organized collection of data. Data from various sources are collected in to a single place, this place is the database. The data is organized into a structure of some sort, mainly according to a database model. The most commonly used database model is the relational model, others include hierarchical model, network model, etc.

In order to retrieve data from a database, one has to use a database management system (DBMS). The database management systems are designed applications that interact with the user, other applications, and the database itself to capture and analyze data. The DBMS is designed to allow the definition, creation, querying, update, and administration of databases. Some popular DBMSs include MySQL, PostgreSQL, SQLite, Microsoft SQL Server, Microsoft Access, Oracle, etc.

While, a database and a data warehouse may seem the same, they are actually different is  a key aspect. A database is used to store data while a data warehouse is mostly used to facilitate reporting and analysis. Basically, database is just where the data is stored; in order to access this data or analyze it a database management system is required. However, a data warehouse does not necessarily require a DBMS. The purpose of a data warehouse is for easy access to the data for a user. The data warehouse may also be used to analyze the data; however the actual process of analysis is called data mining.

Some differences between a database and a data warehouse:

• A database is used for Online Transactional Processing (OLTP) but can be used for other purposes such as Data Warehousing.
• A data warehouse is used for Online Analytical Processing (OLAP). This reads the historical data for the Users for business decisions.
• In a database the tables and joins are complex since they are normalized for RDMS. This reduces redundant data and saves storage space.
• In data warehouse, the tables and joins are simple since they are de-normalized. This is done to reduce the response time for analytical queries.
• Relational modeling techniques are used for RDMS database design, whereas modeling techniques are used for the Data Warehouse design.
• A database is optimized for write operation, while a data warehouse is optimized for read operations.
• In a database, the performance is low for analysis queries, while in a data warehouse, there is high performance for analytical queries.
• A data warehouse is a step ahead of a database. It includes a database in its structure.

Image Courtesy: donmeyer.com, cyber-swift.com