The German tip is most easily distinguished by the metal jacket over the plastic insulator on the tip. The second main difference is that the ring is indented rather than having two holes for the screws as the French tip does.
It should be noted that the two types of tips are not interchangeable. The diameter is slightly different, which is why I suggest purchasing only one type of tip and staying with it, so that, when it comes time to replace parts(and believe me, it will happen) you can easily switch, without needing spares of each type of tip.