I was surprised by how well a simple concept translated to a solid game. Spot-the-difference games feel pretty dead at this point but keeping everything in motion made this much more difficult, especially due to one or two differences that were only present at certain parts of the animation (like the birds.) The first two thirds of the game went pretty fast, but the last third starts getting ridiculous. Would be nice if there were a warning before going back to the menu, and maybe an animated (and quieter) victory screen as winning can be a bit jarring - you just click and instantly see a new screen pop up. The difficulty is also highly variable. It might have been nice to have a few levels ranging from easy to hard, but given how much work went into the art and animation what you have now is probably sufficient. Spam-clicking is too useful; it would be nice to have some kind of cooldown on clicking differences (even if it's like 2 seconds) to discourage it. Offering some kind of zoom feature would have been useful as a means of looking at smaller details up-close, though I can see this not translating well given that the entire background is constantly moving.
Last thing I'd mention with regard to the game experience is that performance is a bit shaky in Ruffle. It's not bad, but the jerkiness can make it a little hard on the eyes, especially when looking for small details. Swapping the graphics from vectors to rasters by exporting and re-importing as bitmaps would probably have improved performance.
Though it probably doesn't need to be said, graphics are beautifully drawn and animated, and the lo-fi music fits. These are definitely the highlights of this submission and it shows.