There's an enormous difference. And it's a good thing F#'s designers chose the latter option; it's a huge win on the interoperability front. Libraries have a tendency to be write-once-use-often, so exporting object-oriented APIs from F# code is way better than consuming functional APIs from C# code.
I think there is a huge way between allowing developers consume F# code from C# and importing all the ugliness of stuff like static members into the language. I don't think it has to be that way.
What's the value of having a runtime with a language-independent intermediate representation if one just adds half of C#'s complexity into F#?
