One of the things i hear most around the shows is:
'German Lops are the same as French Lops - only smaller'
This is WRONG! Their heads are shaped completely differently.  I have managed to get hold of some pictures to show you the difference. (For this reason this page may take a while to load up - please be patient!)

    French Lop 'Roly' - Bred by B & J Lynch

   German Lop 'Diablo' bred by B & D Vrolijks

Head: German Lops have a 'roman nose', which means it is slightly angled and square.  A French Lop has a very curved, rounded head.  The jaw shape is also different.  If you look at the above pictures then you can see the German's jaw is shorted and broader in comparision with the French's.  A German also has more developed cheeks, which helps to give them their appealing facial characteristics.  The crown on a German is also more pronounced as are the eyebrows.  If you look at the face on photos you can see that the French Lops are alot more obvious and defined.

  French Lop 'Riley' bred by B & J Lynch

   German Lop 'Sultan' bred by Kanichen Stud

Ears: French Lop ears are far longer; they have no limit to their length (although I am sure if they started showing French Lops with English lop ears there would be a few objections!)  German Lop ears however have to be a minimum length of 11 inches and a maximum length of 14 inches. (27.96cm - 35.5cm)

Not only are their heads different but so are their body shapes.  I haven't been able to put any photos showing this on here yet but if you compare the pictures in your BRC standards book you should be able to see what I'm getting at.

Body Type: German Lops are alot shorter and have a less curved back.  The neck on a German Lop should not be visible at all, whereas the French Lop Standard states that 'there should be little visible neck', meaning some neck should be seen.

I hope this has helped to show you the differences.