The biggest difference is that her's are lighter weight. I'm no expert on what others may consider 'proper', but I think she looks great whether she's casual in a kilted skirt, tartan skirt or in a more formal and longer tartan skirt.

She'll even bop arounf the Highland Games where I'm competing, in her Sport Kilt. No one has said anything negative--but perhaps that is because I may be standing next to her with a Scottish Hammer in my hand