You might have already known that Nintendo changed a few things when bringing NES platformer Super Mario Bros. 3 to North America—mostly to make it easier—but it's still fascinating to see the changes presented side-by-side.
This video, created by YouTuber Master0fHyrule, does a nice job displaying the differences between the Western and Japanese versions of the classic platformer. Check it. (Sorry about the awful video overlay. We can't find a way to change it.)
UPDATE: YouTuber NintendoPancakes has sent in this video, published in February, which looks a whole lot like the one above.