I will piggy back on this discussion. I have discovered that, although the image resolution is inconsequential when sizing images by pixel dimensions, it still matters if you decide to add copyright information with the type tool.
e.g. I have received images from several people, all sized to 1024 pixels in width, but I wanted to add their names to the front of the images before putting the images into a slideshow. I quickly discovered that, although the images are of identical size when viewed, the names applied vary in size according to the resolution of the image.
Since different makes of cameras assign a different resolution to images taken with that camera, I needed to change the resolution of the images to all be the same before I could add names that appear as the same size. This came as a surprise to me.
Mary Lou