One of the main difference is the Barred rock has a straight comb and the Dominique has a rose comb. Their barring is also different but probably most people can't tell. By the way
Yes that web site is very informative for the Dominique Breed.
If you study that web site you will see that there are few and far between of the old true Dominiques around. I only breed Dominiques and have to do alot of culling to get what I want in a strain, but I am getting there.