It's not a question of what one can do that the other can't. They can both achieve the same thing (they both map to CIL after all). It's usually a question of ergonomics - how much work do you want to put in to achieve the same goal. Things like algebraic data types (discriminated unions in F# speak), currying, etc. all are just a matter of making the compiler do some things that you'd do by hand in a language like C#. While you can accomplish the same thing in C#, languages like F# do it for you so you get both ease (compiler does the work) and correctness (compiler not likely to mess up where you might by hand). I bias towards the F# world for the ease and correctness reasons, but there's nothing stopping a careful programmer from achieving the same thing in the C# world.
