Well from my observation, it really does depends on "where" they come from. For example, all European women are much better dressed than Americans. In both work wear and casual wear. Spain, Italy, in particular comes to mind for their leather goods (shoes, jackets, purses). they are always well made. These things in particular always make a pair of cheap jeans and a shirt look great. In England I found sweaters, gloves, & scarves to be very well made and very beautiful. Which in turn makes jeans or an inexpensive pair of slacks look great.
I also found that most if not the majority of European women wear shoes with some sort of heel which in turn gives everything a more polished pulled together look. Rarely have I seen a European lady wear a pair of tennis shoes!
But in regards to being either Royal or European, I think their "style" depends mostly on thier personality, their likes and dislikes. For example, my style is mostly like Prss Letiza and Prss Mathild. I would wear their daywear to my office. I always wear 3.5 in stilettos to work like Letiza & Mary.
But when it comes to casual, weekend wear, it's all American! Sweat pants, tennis shoes and a sweater of some sort during cold weather. Shorts and a t-shirt w/flip flops during the summer.
So, my very wordy opinion is that it really depends on the "where" and not the "Royalty
