Hedren looks like a disctinctive type of woman. MILLER'S Hedren looks like an overly tanned anorexic and posessess none of Melanies mystery or intrigue.
Sienna Miller does look a bit more worn than Hedren in her two Hitchcock films, but I think this is primarily because the whole style of cinematography, film stock, complicated lighting, and elaborate makeup between then and now is different. (For instance, the old pancake style makeup foundations were matte and quite thick...it actually cracked as the day wore on and the face moved. Miller's makeup foundation, in contrast, is much more sheer and moist, offering a less opaque coverage.)
The actual Hedren photography from the era is flat and velvety, while the HBO photography has much more natural definition (ie, is more "realistic.)
cookie, that is an asutute observation and analysis of filmstock, lighting & makeup of then vs now. I tip my hat. I am old school and a fan of the old in acting style as well. xo lg