there is in terms of collections and performance when interop with java collections, with constructs like Option which I don't like, type interference in Kotlin is stellar, extension functions are cleaner, I don't like implicits at all (none) and feel they can create dangerous coding situations, I like that Kotlin stack traces feel like Java ones, there is not a lot of extra layers of gunk in there, and the religious/conversation with Scala programmers is a turn off to me, some like to talk too much about details of functional rather than getting work done. but that's not scala's fault.