A photo taken of tomatoes was sharp and colorful on both phones; the S8 has a slight edge in terms of contrast and a bit more vivid reds. (tomsguide.com)
In his study of St John of the Cross in The Degrees of Knowledge M. Maritain defined this difference with clarity and exactitude in terms of the contrast between the (poetical) language of the mystic and the (scientific) language of the theologian, and pointed out the disastrous results of reading the former as though it were the latter. (religion-online.org)
In terms of contrast ratio, the iPhone 8's is higher than the Plus, identified as 1400:1 and 1300:1 respectively. (appleinsider.com)