Of course there will be differences, the game is being developed. For example, the old screenshots lack all sorts of post-processing effects, which were compensated for with sharpening and colour filters. Just because something looks different (in this case, you think it's too colourful, iirc) does not mean it is worse on a technical level. If anything, this is the best the game has looked so far in terms of visual fidelity. That's not a downgrade, it's changes being made as the developers iterate upon their product, that's why it's called work-in-progress footage. It's subject to change. It's something we as consumers have to live with, if we want to have more early looks at games, while they're being developed.
The only thing that's happening here is the devs being encouraged not to give us early glimpses of their products in the future.