Do we, the viewer have a different reaction to the media of photography than we do to a painting or sculpture? the

Yes.

Explanation:

Photography is images of things that are already in existence and the there and now and exact.

While painting and sculpture not only takes more times but even if it is of something specific it will never be exact and is needed to be created to exist.

Hence, even though both are forms of art; someone would have a different reaction to something that is created by hands than something that is a photo of something already in existence. One is not better than the other but the reactions would be different and people would probably be more impressed by a painting or sculpture.

I hope this helped. :)

relief sculpture - images are set against a flat background.

a coin is a good example: the inscription, the date, and the figure are slightly raised above a flat surface. the ancient egyptians sometimes carved figures into a flat surface.  

pro: they take significantly less time to make and do not require as much tools or skills as free-standing

cons: not nearly as realistic, as it is not fully 3-d, and does not have the details that a free-standing one does.

freestanding sculptures (also called  carved in the round) are not attached to any  background.   they are 3-dimensional  and fully rendered.