Scala tries a lot harder than Swift to unify object-oriented and functional programming principles.

For example, in Scala operators are (IIRC) implemented as methods on objects, there's a 'Nothing' bottom type that is used for covariant generic parameterization, and ADTs are implemented using inheritance in the form of case classes.

Swift has no top-level object type or bottom type, and a lot of its more functional style features (ADTs in the form of 'enums', value types that enforce immutability) are completely divorced from the object-oriented part of the language.

Very similar languages IMO. Scala is a little heavier on the functional and academic fronts. It's syntax is also much heavier on symbols. In general I think scala has a steeper learning curve. I like scala though. Similar ideas at their core, a mixed paradigm approach. Similar also in that both have a legacy language that they need to interop with. That legacy also bleeds through to both pretty heavily. I also much prefer a native ecosystem vs the jvm.

The one big area that separates the languages is tooling. I personally think Swift's tooling is much better. Faster compilation, faster runtime, faster startup, and better ide tooling.