Fundamentally it's a language oriented around blocks of statements rather than composition of expressions. Additionally, it takes a different approach to the mutation problem than FP languages: where FP seeks to make most things pure and push mutation and side effects to the edges of the program, Rust uses its type system to make such mutation and side effects more sane. It's an entirely different philosophy when it comes to programming. I don't think either approach is necessarily better, mind you, just a different set of tradeoffs.
I'm a professional Haskell developer and am very much immersed in FP. When I read Rust code, I have to completely shift my thinking to something much more imperative. Whereas if I read, say, Ocaml, the difference is mostly syntactic. This isn't a slight, mind you. I quite like Rust. But it's a very different paradigm.