A: A data warehouse is higher on the pyramid of big data storage, in terms of size and function.
A database is typically used to capture raw data for real-time use. It’s also a smaller repository, and the types of data collected there are more specific.
A data lake is used to store data for later. You can throw whatever kind of data in any format into data lakes, and then, at some point in the future, you can extract value from that data.
A data warehouse is even bigger than a database or a data lake, but is used to hold historical data, not real-time data. The best way to use a data warehouse is for connecting data across channels.