The first time I saw the above poster I thought the background was a photo of actual milk being poured. Seemed like a lovely literal interpretation of something one wouldn’t expect to be interpreted literally.
Well, it’s not milk. But I imagine the designer was conscious of the resemblance and got a kick out of it.
Outside of that the poster is all about Sean Penn as Milk. It’s a safe sell, since this is probably the main appeal of the film to the broader audience and is not likely to turn anybody off. It works because Penn is great, even in this still image. But it’s too safe to really be an outstanding poster.
The other poster is basically the same, but loses the lovely white background and substitutes it for some blue and photos of the rest of the cast. I like the white better myself.