Beta versions of Super Mario 64
Here, the design of Whomp's Fortress is identical to the final version of the game, but the look of the floors look completely different. The HUD (Heads up display) is also different. It looks like the background is just white, nothing else. Also, I don't see the red coin that is to the right of the bridge in the final version, but it may have been collected.
Whomp's Fortress, of course, but in these shots, you can see the first version of the Power Meter, which is in the shape of a shield, says "POW", and shows a number. There is also red carpet shown here. This beta version is the same as the above.
More Whomp's Fortress. Again, same design, different looks on the ground. The yellow coins that appear on this white ramp in the final version aren't there.
Last shot from Whomp's Fortress. Colorful looking, really, but pink on the ground/floor...doesn't work, sorry. Good thing it was changed in the final version. The tower, like the the rest of the level, has the same design as the final version, but rather than a totally different look, the only difference here is that it's green.
These shots are from the Bowser scene in Bowser in the Dark World. Mario and the platform Mario and Bowser stand on are the same, but Bowser himself has different looks (But the same design as the final version). There are also no bombs, so I don't know how the player could defeat Bowser in this version (Probably by throwing him of the platform). The background is also different. It is blue, with clouds. To be honest, I actually liked this background quite a bit better than the final version.
The first version of the castle. The windows are different, and the bottom of what we see of the castle in this shot is pushed inwards. There is also no picture of Princess Peach, and on the left, there is a platform or something that didn't make it to the final game. At least not in that location.
It's Cool Cool Mountain, but unlike Whomp's Fortress, it's completely different. The Penguin Models are different, the snow is more colorful, there is a fence which never made it into the final version, the background is different and there are weird pyramids behind Mario.