One of the best new features in Android Oreo is the new Adaptive Icons system. Starting now, developers can create a single icon for their apps, then your launcher can stylize those icons in a broad range of shapes to match your system theme. Most home screen apps haven't added support for this feature yet, but Nova Launcher just threw its hat into the ring.
The stock home screen app that comes with your phone is nothing compared to Nova Launcher. Not only is Nova faster, but it's got tons of customization tweaks like gestures, adjustable grid sizes, and icon packs, just to name a few.