Think of Power BI as more of an eco-system than a single tool. There are three components: 1) Power BI Desktop, 2) Power BI Service, and 3) Power BI Mobile. The desktop application is where users do data manipulation (maximum 1GB), analyze the data and produce interactive dashboards and reports. The output then gets published on the web to Power BI Service or embedded into a web page for other Power BI users and non-users alike.