S8 have have glass back and a metal frame, with the glass on both sides. Whereas, iphone7 has similarly premium design,with a metal unbody that's slim. Samsung S8 has a 5.8 inch sccreen with a resolution of 1440 x 2960. Whereas, iphone7 has 4.7 inch Screen with 750 x 1334 resolution.
http://irepair.com.sg/blog/iphone-8-concept-has-a-unique-place-for-camera/
http://irepair.com.sg/blog/samsung-galaxy-s8-what-we-know-so-far-about/