Both beers currently in the (fermenting) fridge are being fermented with Wyeast Greenbelt. The yeast for both is identical, grown from the same slant and in the same starter until the 2nd-to-last step of the starter process. While the wort for each beer was different, its surprising how different each looks while it is fermenting.
The Amercian Black Ale kräusen is thick and yeasty, looking much like a top-cropping English Ale:
While the Widbier kräusen is light and fluffy, looking more like foam from shaking the fermentor than a yeast-käusen: