Usagi Yojimbo DojoBoard

Living in europe and not reading alot of other us monthly comics I have always collected the Usagi Trades because they are alot easier to get around here.
So I have never held a single issue in my hands.
Recently a friend gave me Paul Chadwicks 'Concrete: Think Like a Mountain' Miniseries collected in single issues and I noticed stuff that I don't believe is in the trades like a letters page, some minicomic in the backand on the last page 'Finish Line' a colum for news written by Dark Horse staff.
So I wondered ss there something similar in UY?
The main difference I can see is that the single issues come with the colored covers and I guess that the crators notes that are in the books are also in the singles. But what else is there, a 'the story so far' paragraph, a letters page, advertisments, a back cover?
Curious,
E.

Edit: While catching up on the postings since my last visit I looked at a few of the interviews of Mr. Sakai and read about the go game error that was corrected between the single issue and the story collected in the book. Has somethig similar happend at other times? I know alot of people who like to tinker with new editions of their works, ranging from stuff like corrected spellings to things like Han Solo shot first/at the same time/after.

Yes, there are quite a few differences between the trades and the single issues. First and foremost to me is the size difference. The single issues are larger, doing Stan's art more justice. The color covers, letters column, pin up art, and photos of Stan's appearances round out the other differences. In the Fantagraphic run, there were even back-up stories by other artists that, for the most part, I don't believe were reprinted elsewhere. Once in awhile you'll get art differences, but these are rare. Some of the more notable: 1) UY vol 2, which was published by Mirage in full-color, was reprinted in black-and-white for the trades, with the artwork touched up quite a bit. 2) Some of the earlier Albedo comics had art that was touched up because at the time Stan was using zip sheets for tone work. This was replaced by brush work or simply removed. 3) Sometimes artwork was done specifially for the trades to provide transitions between stories. One notable one was in UY Book 2, where a couple pages were added to transition a Young Usagi back-up story from one of the earier Fantagraphics issues. There was also some transitional work done for Lone Rabbit and Child, which appeared in UY Book 1. Such transitional stuff is very rare now since Stan is much more aware of the issues going to reprint as trades than way back in the 80s. FOr the later stuff you can expect very little differences aside from corrections and such as you noted.