The front and rear lights are the most noticeable change. The front lights taking notable inspiration from the new CLA-Class. Not all too surprising considering the GLA is pretty much a crossover version of the CLA with the same drivetrain and similar pricing. Unfortunately, the same thing that happened with the CLA-Class which is a much more toned down design than its concept is happening with the GLA-Class. This is what happens when a concept moves to production form.
Check out the design in the video and design sketches below.