You can e.g. use the Matcher or the ChangeDetector.

There is also the custom transformer UpdateDetector on the FME Hub.

You tagged your question with "Inspector" so maybe you just want to visualize the two datasets differently in the FME Data Inspector? That's easy enough. Either use an Inspector for each and set a different color inside its parameters, or set the colors inside the Data Inspector by clicking on the 'grid' type icon in the left hand window. That advantage of that is that you can change the icon size and style too (in FME2016)