Microsoft SQL Server Data Tools provides an integrated environment for database developers to carry out all their database design work for any SQL Server platform within Visual Studio. The SQL Server Object Explorer in Visual Studio offers a view of your database objects similar to SQL Server Management Studio. SQL Server Object Explorer allows you to do light-duty database administration and design work. You can easily create, edit, rename and delete tables, stored procedures, types, and functions. You can also edit table data, compare schemas, or execute queries by using contextual menus right from the SQL Server Object Explorer. Database developers can use the SQL Server Object Explorer in VS to easily create or edit database objects and data, or execute queries. The Microsoft SQL Server 2012 Data-Tier Application Framework (DACFx) is a component which provides application lifecycle services for database development and management for Microsoft SQL Server and Windows Azure SQL Databases.
Reference: Pinal Dave (http://blog.sqlauthority.com)