It appears as though Super Mario Odyssey is having a bit of an identity crisis, just yesterday it was reported that the ESRB had rated the game as 10+E (Everyone over 10), following a similar rating in Australia. This was odd because, until this point, every Mario game had received an E for Everyone rating.
Now, it appears that Nintendo has changed the final box art of the game, despite the fact that it's been plastered all over the place, as a marketing tool. In the lower left corner of the older box (which I've circled to make it easier), Mario can be seen sporting a large sombrero, but in the newer box, that image has been replaced with a picture of Mario underwater with a snorkel.
The change was first noticed by the user on Twitter named Nibel. There's been no word from Nintendo on why the change was made so late in the game's marketing push, however, it's clear that this new box is the one we're going to start seeing everywhere. Companies like Target, GameStop, and Amazon, have all updated their product listing with the newer box art, while Best Buy is still lagging behind with the older box and Walmart is just using a picture of Mario and his hat.
Perhaps the most interesting piece of this puzzle is that Nintendo themselves are still showing the older box art on their website. We have no idea why these little, last minute changes are being made, but Odyssey is clearly shaping up to be a completely different Mario experience, especially with the announcement that the classic "game over" screen had been removed.