I might be wrong but I will give you my personal opinion: multi-funcional-(functional) is an adjective and it is used to say that an object/machine/system works properly while multi-funcion-(function) is a noun and it expresses somebody/something's purpose<duty as well>. You can say that the new watch created by the IPhone company is multi-funcional since it can do multiple(multi) actions(functions). You can use multi-function on the other hand in order to express quite the same thing concept as an example ''a multi-function printer'' The only difference I can see between the two of them is at the grammatical level. I do not know what to say about the particular example of the '' employee''. The concept of a person that can do many things is right but I'm not sure if multifunctional is the right word in order to describe it since functional sounds more technological if I can put it this way. I hope you ll find my answer useful.

They mean the same thing and both are formal.