Lee, Jeff has mentioned the 'difficulty' setting, this makes the resistance harder or less. only 6% max yesterday.
You still need to make the power, either by high rpm cadence or outright leg strength, it just moves you into a different area of gearing for your bike/type of rider.
I leave mine on the middle for the kickr because its so similar to trainer road and outdoors.
I think Boxers said he upped his difficulty to maximum and then felt the hills were much harder.
Zwift is very much like outdoors once you've got it setup. At least you were using real power numbers from the hub PM