Which Olsen — Mary-Kate or Ashley?

I used to pride myself on being able to tell the difference between the Olsen twins, but lately I've found the more I see them, the more I doubt my abilities. Clearly, this is an important distinction to be able to make. An Olsen twin was spotted in LA yesterday and while my initial instinct is MK for sure, it totally could be Ashley. So which little blonde has her hair in her face — is this Mary-Kate or Ashley Olsen?

Flynet