Q:

SharePoint 2013: Start a workflow when a value in specific column is changed

I would like that  my workflow will run only if a value on a specific colunm will change.
Is there a way to do it without using a third colunm ? 

A:

You can check the following link :
http://office.microsoft.com/en-us/sharepoint-designer-help/watch-this-run-a-workflow-when-a-specific-field-changes-HA010256419.aspx
I think you might need some other hidden column to achieve this in sharepoint designer workflow,.
Otherwise, you may create an itemupdating/fieldUpdated event handler and start the workflow programatically.

