A database is a structured data set than can be accessed by many potential authorized users via a computer system or network. The most common type of database is a relational database, which breaks data into separate tables, each containing a unique list of the items stored.
It is possible to create and store data in Excel, but it is preferable to store data in a database and simply connect to it in Excel when you wish to perform data analysis. Tableau is a data visualization tool and displays data in a visual format rather than a numerical format like Excel. Tableau is great for exploring data and identifying trends and outliers, as well as presenting results when sharing the story.