I have done a small project using the sashiko thread and it is supposed to lay flatter and smoother than perle cotton or embroidery floss. Since I've only used the sashiko I can't compare but if I continue to do sashiko I am going to use the perle cotton because I have it and it is available more easily than the sashiko. I got my sashiko thread from the quilt store offering classes in sashiko.