The reason why your pictures are looking different is the released one is renderd at high settings from the graphic engine they use.
For exampel one faktor woud be the resolution. Your pic has the resolution of your Monitor , the relesead picture is maybe rendered with a resolution of 8000x8000 pix. the detail on the released one are much higher. In game every picture that you see is rendered for exampel at 1280x768(depends on what you set ingame), the reason is to keep your performance high to avoid any laggs.
different colours: every pc have a slightly different gama calibration, this coud lead to this effekt. You can tweak your gama at graphic settings, monitor settings..and ingame aswell. or later in Photoshop.
I guess the released pic is over-worked in Photoshop where you can tweak all that stuff.
I dont knew what render engine they use but i for exampel knew Vray. In Vray you can define with what Quality you render a picture. Vray simultate naturel light under considering the physical laws.
Bescuase of this it is difficult to create the same render szene ingame, you woud have to position everything in the same way, distance form son to objekt, colours, incidence angle.... there a much more settings which you cant acces as a gamer.
If you want to get more intel intressting keywords are "global illumination " ; "color bleeding" for exampel