Translation:It is not this actor who is famous but the other one.
As a person who speaks English as their first language, this is an extremely difficult sentence to decipher into the correct Hungarian structure. Sentences that are somewhat nonsense (like this one) or are in a structure that seems like it would be spoken 100 years ago, would never be used in normal/regular English conversation today. They are not helpful in learning a foreign language.
...sentences like this are why I suspected machine translation of some of the items.
Yes, you'd have to say "It is not this actor that is famous" or something like that. "Not this actor, but the the other one" is the gist of the sentence. You could complete it to a more normal-sounding English sentence by putting the verb at the end, I suppose: "Not this actor, but the other one is famous." But if I were treating this as a translation exercise in real life I would turn the order around so the positive part comes first: "The other actor is famous, not this one." That often seems to give the most satisfactory result when you're translating nem ... hanem ... things from H. to E.