Kristen Stewart and producer Arthur Cohn disagree on which role was more difficult for the actress, her Twilight character Bella Swan, or her The Yellow Handkerchief character Martine.

Bella is the love interest of vampire Edward Cullen in the hugely successful Twilight movies. Martine is a lonely, rebellious teen. The now 19-year-old Stewart landed the latter role when she was recommended by her Panic Room co-star Jodie Foster.

Arthur Cohn, producer of Handkerchief, which hits theatres Friday, told MTV, “Kristen had an enormous sensitivity for an extremely difficult part. With all respect to Twilight, I think this part was infinitely harder to pull off.”

Stewart, however, disagreed. “No, I would say definitely not,” she told MTV. “It’s so hard to compare roles – [playing Bella] was difficult for other reasons.

Stewart says the Handkerchief shoot was “so much smaller, it was so personal.”

However, she points out, Martine’s on-screen life is a snapshot, while Bella’s spans four (maybe five) movies and several years.

“Bella has definitely got more [complexity]. Bella has more to do. [As an audience member], you’re with her for years of her life; you’re with this girl for two weeks — not even, a week.”

She goes on to tell MTV, “When I play a character, I have to know her very well. Maybe [Martine] is mysterious to the audience [because she is less explored than Bella], but I know her very well. I know her for a brief period of her life. But then, I have to explore what it would be like to live [Bella's] life from the age of 17 to 21 or 22.”