The uniforms are instantly recognizable to the French or Belgians, generally speaking. They are featured on tens of thousands of public memorials in cities, towns and villages, often with large towns and cities having several monuments to honor and commemorate the dead of the Great War. The are omnipresent in urban landscapes and form part of the backdrop of everyday life.
Out of the somewhat 30 000 French communes/municipalities, it is said that only 5 did not erect a monument to the fallen of the Great War.
Just as Americans instantly recognize the difference between Confederate Gray and Federal Blue, which is only a color, so do the French instantly recognize the distinctive casque Adrien, the Adrien helmet of the French and Belgian soldiers of the Great War.
I believe the point was that they were both wearing the same uniform, with the same unit number, and both had mustaches.
Hitler! C'mon, I'll buy you a glass of lemonade.