(Cover) - EN Fashion - Mary-Kate Olsen says the main difference between her and her twin Ashley is that Ashley can walk in high heels.

The sisters began their careers on American television show Full House in 1987, when they were just nine months old. They went on to forge successful careers in fashion, and run labels The Row, Elizabeth and James and Olsenboye together.

Despite loving clothes, Mary-Kate admits finding certain footwear intimidating. She worries she will fall when wearing towering heels, explaining Ashley is less anxious. “For a start, Ashley can walk in heels and I can't,” she is quoted as saying. “She's really graceful while I'm such a klutz. I think generally now people see us as individuals whereas years ago people couldn't see the difference. But it's weird because we've always been two different people."

Mary-Kate and Ashley are worth an estimated $100 million. Much of their wealth has come from their clothing lines, which is what Mary-Kate considers to be her day job. She recently admitted viewing fashion as a “mask” which shields her from prying eyes, and loves spending time coming up with new pieces for the ranges.

“It took us a year-and-a-half to make the first T-shirt,” she laughed. “This is my day job. The Row is where I go every day.” (C) Cover Media