What happens if the two images are different sizes?
Both images are scaled down to match the smaller image's dimensions before comparing. If the two images have very different aspect ratios, this scaling can distort the comparison — for best results, compare images with the same aspect ratio.
What does the sensitivity slider control?
It sets how large a color difference must be before a pixel counts as "different." Lower sensitivity flags only major changes; higher sensitivity flags even subtle ones.
Can I use this to check if two exported files are identical?
Yes — a 0% difference result means the visible pixel content is identical, even if the file bytes differ due to compression.