You are spot on Marco. The only thing I would add Fellbeast is that a gravel/adventure bike is great off road if that off road is relatively smooth. You refer to "all things off road" where perhaps the surface is very rutted or has lots of stones or rocky sections where suspension would be handy.
Over a small section you would probably get away with it but being rattled for hours on end is not fun and a Mountain Bike could be an option. Again, as Marco has alluded to, smoother road type tyres are available for Mountain Bikes and roll well, but enable you to travel faster, more comfortably, over rougher surfaces.