Microsoft has recently published new Feature Comparison Tool. Before the newest release, we could compare up to Microsoft Dynamics NAV 2013 R2. Now we can make a comparison from NAV 4.0 to NAV 2015.
You can select only your current version to see existed features. Also, you can see all features of your future versions. Or you can make compare all versions on the same place to see what you are missing.
You can try it on the following link.