I am new to the chowhound boards in general, and I am sure there are those with more experience in this area, but I believe that ground bean sauce and brown bean sauce are (generally) the same. Depending on manufacturer, they usually contain primarily soybeans, salt, a thickener such as wheat flour a little sugar perhaps and that is about it.
The "ground bean" sauce usually implies it is finely pureed with no remaining soybean chunks. Otherwise, it may or may not still have some chunky bits remaining. For example, I tend to like Koon Chun brand, and get their plain old "bean sauce" which still has unground bean bits and a wonderful deep earthy flavor. Be sure to not mistakenly get "sweet soybean sauce" unless the recipe specifies it, as this has a sweetness nearing that of Hoisin sauce without the additional spices of Hoisin.
I would recommend getting a few different brands/varieties and see which one suits the style of Chinese cooking you are most into.