Emma Cook has a very narrow band of color edging the falls. Some flowers shown are amoenas with a zonal pattern near the beards. EC is an amoena with A VERY NARROW band of color. The difference is width width of color on the falls.
Here is my list of "Emma Cook Pattern" cultivars based on our database. Love Tom's explanation on the categories. I was going to go with the "English language. All sorts of rules that get broken every which way.