iPhone 7 Plus alongside its predecessors giving an understanding where the two stand in of size. Also, a live image has surfaced online reiterating design rumours, and both the devices were also reportedly certified on FCC revealing model numbers.
Onleaks has Galaxy S7, as well as the iPhone 7 and iPhone 7 Plus. Just to compare, the Galaxy S6 had a 5.1-inch display, and the Galaxy S7 had a 5.2-inch display. While the predecessors have significantly smaller displays, the form factor of the Galaxy S8 with a 5.8-inch display increases only a little, and the large difference in display size is due to thin almost bezel-less nature of the smartphone.
In comparison, the iPhone 7 with a 4.7-inch display looks too small alongside the Galaxy S8. The Galaxy S8+ with a 6.2-inch display looks head to head with the iPhone 7 Plus with a 5.5-inch display, again because of more display real estate. The tipster has also compared the Galaxy S8 and Galaxy S8+ with the Pixel and Pixel XL, Huawei P10, LG G6, and Nexus 6P, and you can see the comparison schematics below.

Photo Credit: Onleaks

Photo Credit: Onleaks
Furthermore, tipster IceUniverse has shared live images of the flagship from various angles. The image pretty much reiterates previous rumours of a large dual-edge curved display with the iris scanner in the front. There's also a dedicated button seen in one of the images for Samsung's AI-based virtual assistant, Bixby.
Lastly, the devices have reportedly been certified by the US FCC as well, and the Galaxy S8 is listed in three variants with model numbers - SM-G950U, SM-G950U1 and SM-G950W. Similarly, the Galaxy S8+ is also listed in three variants with model numbers - SM-G955U, SM-G955U1 and SM-G955W. The listing also confirms the arrival of wireless charging.
Previous specifications have also been leaked, with the smartphones tipped to sport Quad HD+ Super AMOLED displays, a Snapdragon 835 SoC (or a Exynos 8895 SoC), 4GB or 6GB of RAM, 64GB of inbuilt storage, 12-megapixel dual rear cameras, and an 8-megapixel selfie camera.