Because they’re both based on the Kodi core, they have many similarities. LibreELEC uses the default Kodi design (or skin), so it's more likely to resemble other Kodi systems you have used. It's also a more lightweight option, so it may perform better on lower-powered Raspberry Pi models.
To make it easier, you can choose the default Kodi skin by clicking Settings on the left, choosing Interface from the menu that appears, and then choosing Skin. Click Skin in the main part of the screen to open the options and choose Estuary, which is the Kodi default.
You can change back to the OSMC skin from Estuary by clicking the Cogwheel icon at the top of the menu on the left, choosing Interface Settings from the menu that appears, hovering over Skin on the left, and then clicking Skin in the main part of the screen. You can exit any of the menus by pressing Esc.
To start setting up your media center, create an SD or MicroSD card with NOOBS Lite on it, and then use that card to install LibreELEC.When you first boot up LibreELEC, you'll be guided through its main settings, including its name on the network, the network connection itself, and the remote access settings (so that you can access files on your device over the network).