Jack Kirby's version is unmistakably dynamic and powerful. The Leader's sitting inside that Kirby cosmic contraption ready to blow Greenskin to smithereens.
Herb Trimpe's version (sorry this is best image I could get) has the same pose as Kirby's poster, the same angles and design. Trimpe's touch is seen on the Hulk's face and the inking on the body is more rounded and less square.
Did Herb Trimpe ink over the pencils provided by Kirby for the original? Why were there two posters? Let me in on the secret if you know. Nuff Said!