Online everyone says the iPhone screen size is 480320 pixels.
When I create a box in Photoshop using 480320 pixels, the size
looks different then my actual iPhone screen size.
My iPhone screen size looks more narrow.
Am I missing something?
Pixels are different sizes on different displays, because different displays have different PPI (pixels per inch). So 480x320 will look different on an iPhone (163 pixels per inch on a 3.5 inch display) than on a 24" widescreen monitor at 1920x1080 (~91 pixels per inch).