SQL Server Management Studio 2014 - Show same .sql file in multiple tab groups
To my knowledge SQL Server Studio doesn't have a clone/compare feature. Having said that, it appears that SoftTree makes a product that integrates into SQL Server Studio allowing you to use Notepad++ as the editor (which looks very cool):

http://www.softtreetech.com/sqlassist/more_screenshots.htm

http://www.softtreetech.com/sqlassist/


Note: I have zero affiliation or investment with this company.

SoftTree looks to be a bit pricy. However, you can get a free plugin to run SQL code from Notepad++ here (I'm liking they way this looks and may have to try it myself):

https://github.com/gutkyu/NppDB