I'm trying to figure out how to subtract two images in Photoshop so that the result is an image with transparent layer. Basically it all boils down to the fact that if color of the pixel is the same, it sets pixel in transparency layer to black. What's the easiest method to achieve this kind of result in Photoshop? Below is a visual example of what I'm trying to achieve (a figure with transparent background, NOT WHITE)
If you use the difference blending mode, you'll get black where the pixels match, and non-black where pixels do not match. In your simple example, you'd end up with a black background and the red circle would be cyan (inverse of red).
You could invert that image and then you'd have white background with your red circle (for this simple example anyway)
I don't know of any way of ending up with transparent background rather than black/white. You'd either have to save as GIF and set that color as transparent, or use select color range, select the background, and delete it.