Wert and all, I think I can show from a couple of scans of an unused 210 I have and my certed copy of a 211B, the cross-hatching that alub posted from Bill Weiss' website:
Here is the lower left side of the 210. Notice the background of the stamp North and Northwest of Washington's shoulder:

Now here is the 211B. See how the impression is so much cleaner-- remember that these were special printings, and they look very proof-like with perfect impressions. Notice the diagonal lines (N.W. to S.E.) go all the way to the shoulder (cross-hatching):

To show the differences in the impression, here is the 210 on the left and 211B on the right.

I'm not a Bureau collector, but I had a chance to pick up a flawed copy of 211B (it has a tear on the upper left) for less than $100, certed, so I bought it, just so I could understand the differences and hopefully find one of my own someday.
Hope this is helpful,
Ray