"For Visual Studio 2013, there are two different products that are called "SSDT".
One SSDT includes tools for relational databases in Visual Studio, with features like Data Compare, Schema Compare and SQL Server Database Projects. The other SSDT, referred to as SSDT-BI, includes the BI project types for SSRS, SSIS and SSAS. The SSDT relational tools are included in Visual Studio's setup experience as a checkbox option, but the SSDT-BI tools, on the other hand, are only available as a separate download. This "two SSDTs" thing caused a lot of confusion and was widely regarded as a bad move, so for Visual Studio 2015 we've made some changes." -- MSDN: How to install SSDT