A screen topi, cap is a foto from a movie atau TV show, whereas a foto is like just a foto of the celebrity/band/whatever from a foto shoot atau public appearance.
I think a screencap is when anda just take whatever is on the screen and make it into a picture. I mean like for a screencap you'll literally take your camera and snap a pic of the screen, atau you'll hit ALT+PrtScn to make a topi, cap of your computer screen. Plus, screencaps are of the entire screen, normally. No cropping atau whatever.
I think foto-foto are lebih edited and planned, rather than a Rawak pic of a Rawak scene.