Externally, there’s not much change, but internally, the type system has been completely redesigned. It should be easier to autocomplete in your IDE.
Additionally, there is a new component, the Bottom App Bar!
The upstream library, MDC-Web tends to only implement components that are meant to be rendered on larger displays, such as desktops. As such, components that are exclusively meant to be for mobile devices, like Bottom App Bar, are left out. It is SMUI’s ultimate goal to provide 100% of the Material Spec in Svelte though. In my pursuit of this goal, SMUI 7 fully implements the Bottom App Bar according to the Material Spec. Even down to the notched bar slowly losing its notch as it tucks away leaving the FAB displayed during a page scroll.