Is an officer the same as a hero?

Depends on what a hero is in the game you are mentally comparing an officer to. I find the game is not drastically different from Vikings or Throne, it just adds window dressing etc... plus enough extra bonus events to ensure one maximizes "sunk cost." (google it)

So in that respect, yes, officers are like dumbed down versions of a hero. Because officers are more specialized, however, one needs more of them while also acquiring some know-how on how to employ them.