Scott had a huge following in the US.
According to the book, several famous American shooters used them - Captain A.H, Bogardus, a Mr. C Macalester - and Scott guns did very well at a number of top American shoots, including and International Gun Trial held in New York in 1873.
I have a reprint of a W & C Scott catalog from 1872. Along with testimonials from shooters from England, the catalog is filled with compliments from shooters from Boston, Worcester, New Orleans, Lexington, KY, and one from a Mr. Van Gieson who lived in Whitewater, WI.
Wm. Read and Sons in Boston was one of Scott's US agents for a while.
I think the stock dimensions were the big difference. I don't know of any others - probably just patent marking, maybe importer's names, etc.
Here's a Scott that was retailed by a firm in Paris:
http://www.leroymertz.com/photo.php?id=1738_0_2_0_M28The gun does not have Scott's name on the rib. Instead, it has the retailers name and Paris address.
OWD