I don't know if it's harder but when you're playing a real person you want to honor their memory - even if they're a criminal or someone that the public loathed. That can be challenging.
“I never wanted to stay in one genre; I never wanted to be pigeon-holed or defined as the actor who only worked in one genre. I want to be able to work in all different genres. For me it's fun, and that's how I grow as an actor.”