Slight layout changes, typically some top and/or bottoms of panels cropped slightly in height so the pages fit the UK page size.
The two chapters are printed as one in this reprint.
"The Hulk Strikes!" chapter is from the reprint from Marvel Collectors' Item Classics (Marvel, 1965 series) #14, you can tell this due to the text blurb caption at the bottom of the page at the end of the chapter. Also this UK reprint does not reprint "The Hulk Strikes!" 1st splash/title page.
Message from Stan Lee about the launch of Marvel U.K. and details of a mystery gift offer