Power BI started after the following add-ins for Excel:
- Power Query – ETL (2010 +)
- Power Pivot – Modelling and analysis (2010 +)
- Power View – Interactive reporting and visualization (2013 +)
Now Power BI as a stand alone desktop application. Also an Excel Add-in.
Power BI Desktop is simply a standalone desktop application bundling the add-ins above in a package with no dependence on your Microsoft Office installation.
Power BI provides Power BI Service.The Power BI Service is the web portal. This includes Power Views, Dashboards, etc.