The armorial bearings of the newly elected Abbot-General of the Order of Canons Regular of Prèmontrè (aka the Norbertines) the Most Rev. Josef Wouters, O.Praem., former abbot of Averbode. This coat of arms was originally designed by Luc Duerloo and contains charges on a fess normally associated with the Community at Averbode with the addition of personal symbols (the lance head and plow blade). The impalement here is with the arms of the Order. I understand that, as Abbot-General, he has decided to use some other arrangement which, oddly, combines the symbols for Averbode with the arms of the Order and omits any personal symbols whatsoever.
EXARANDORUM 
Is there a reason for the discrepancy between the number of tassels on each?
Yes. Generally speaking the galero of abbots, ALL abbots, has 12 tassels. There are some who try to assert that those abbots who have the honorary title Archabbot, and there are very few of those in the world, should, like archbishops, use 20 tassels. Heim sees no real justification for this. Other authors, like McCarthy, assumed, erroneously it turns out, that Abbots General should be seen as “outranking” other abbots and are, therefore, entitled to 20 tassels as well. There could, at least, be some argument here since an Abbot-General does have jurisdiction over his Order. However, a term or two as General does not change what kind of Abbot someone is. Rather, it is a distinction of jurisdiction alone. For example, McCarthy asserted that the Benedictine Abbot-Primate should use 20 tassels but that was based on the mistaken belief that he was, like an Abbot-General would be, head of the whole Order. That is not the case. The Abbot-Primate of the Benedictines is a figurehead with no jurisdiction. That’s WHY he isn’t called a General. He has Primacy of place and of honor so he is called a Primate. So it seems the creator of the second drawing subscribes to this theory that Abbots-General are equivalent to Archabbots and furthermore to the idea that Archabbots should use 20 tassels. Personally, I agree that it would be a nice idea if, like archbishops Archabbots used 20 tassels. However, I know that in practice it is not done. Full stop. Similarly, I do not agree that Abbots-General should do the same. They are not equivalent to Archabbots. In addition, as head of their orders during their term they enjoy the same jurisdiction as the General Superior of any other Order or Congregation. Those Superiors are permitted 12 tassels already so Abbots-General should be content with the same. Who knows? Maybe a new trend will catch on but I doubt it. People may continue to disagree on this point but the practice at this present moment and already long-standing custom is that all abbots, abbots-general, abbots-Primate and Archabbots use a galero with 12 tassels.