How to return the difference (columns) between two databases or tables
You can use the applications listed in comments, or use SQL Server Data Tools. What I like about SSDT is it is a native SQL Server development environment, works well with source control, and has a really good set of features for database development.

You should be able to install from your SQL Server 2014 media or just download it. You can then use Schema Compare between database projects or deployed databases. In the example image I have compared two dev servers, and after selecting a Procedure that has a detected difference, I can inspect what has changed. You can script out the update and inspect or edit it or simply push the change to the target server. You could also import either into a database project and put it under source control.