Just stumbled over https://ttu.github.io/kotlin-is-like-csharp/ . Probably intended by the author of the article, both languages look very similar, but where does Kotlin excel/outperform on a language level compared to C#?

It is a popular genre. http://nilhcem.com/swift-is-like-kotlin/

Oh swift looks even more similar. :-)

The async/await example in the C# comparison is interesting. It almost looks like the Kotlin example was written to try and match the shape of the C# one, which is sort of missing the point. Highlighting the differences between the two approaches to concurrency would better show off the strengths of Kotlin coroutines.

C# is like Java (they're both like C++ with similar design goals). kotlin is also kind of like Java. Don't think there's any similarities beyond things they both share with Java