Kate and Pippa Middleton make for one decidedly fashionable duo. One opts for prim and ladylike; the other plays up a more casual-chic side. Together they are truly a stunning duo. And they rocked the fashion world in 2011, stepping into the limelight after a flurry of attention from the royal wedding in April. 

First, there is Kate. Kate Middleton is not your average duchess. 

Instead of draping herself in million-dollar exotic silks and all the Crown Jewels, Middleton opts for simpler, budget-friendly styles while performing her new role as Duchess of Cambridge.

Of course she splurges every now and then, but you will typically see the lovely brunette in extremely unpretentious - sometimes high street - fashions. Some of Middleton's favorite brands include Zara, LK Bennett and Whistles. All lines are rather inexpensively priced, which makes it easy for the 'Every Girl' to copy her coveted style.

The 29-year-old effortlessly blends her country girl roots with her new royal status. Thus, her outfits are sophisticated and timeless, yet youthful and modern.

Then, there is Pippa. And, in 2011, she caused quite a stir.

The sister of Kate Middleton, Duchess of Cambridge and wife of Prince William, has become an international sensation ever since appearing at her sister's wedding wearing a curve-hugging, buttercream Sara Burton of Alexander McQueen gown. 

She was instantly dubbed Her Royal Hotness on blogs around the world. Most of them were referring to her extraordinary bottom. But we think Pippa's style is just as gorgeous.

Pippa Middleton has that quintessential girl-next-door look. She has an athletic build and she opts for more natural make-up choices. Her style could best be described as casual chic. Some of her wardrobe staples include: ballet flats, sunglasses, sheath dresses, blazers, and brown boots. She usually sticks to primary colors -- black, red, brown, navy, and white -- and steers clear of wild prints and neons. 

Despite the fact that Vogue chose Mary-Kate and Ashley Olsen as its most stylish sisters of the year, we think Kate and Pippa Middleton take the crown. 

Here is a look back and the sisters' best fashions from 2011.