The X screen size is the same width as the 8, with both at 375 points across. The X is just a little taller.
In comparison to the 8 Plus, the 8 Plus gains True Tone "true color" display technology, as well as an upgraded camera, the same A11 SoC and wireless charging capabilities as the iPhone X.
The X has a better camera, oled screen, animoji, Face ID, and edge to edge screen. Photos and videos taken on the 7 Plus will be cropped on the X, unless you tap the screen twice. Then you see the images entirely, but smaller and not edge to edge. The 8 Plus actually has a slightly larger screen in total space. It's definitely wider than the X. I prefer the wider screen with the 16:9 aspect ratio. Bezels don't matter to me, and neither would the notch on the X. The only feature on the X that the 8 Plus doesn't have that I would like are the animojis. I would have fun with those. Here's the screen difference between the 8 Plus and the X.
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For me, the X would feel too small, more like the 4.7" models. I have tons of custom wallpapers that would no longer work on the X. If the X had the same screen width as the 8 Plus, I'd be looking at it a lot harder. It's just too tall and skinny for me. I don't like my women that way either.