Dreadnought's conservative structure and revolutionary system

Was HMS Dreadnought structurally very different from the Lord Nelson class?

Not greatly: her internal subdivision and armor scheme remained evolutionary, even though the combined armament and propulsion package created a major change in naval competition.

Dreadnought remained heavily subdivided like her predecessors and may even have carried slightly thinner armor spread across a greater area. Her rapid construction was possible because much of the underlying structure and equipment remained evolutionary. Proven 12-inch weapons and other available components reduced development risk. Her importance came from combining those established elements with turbines and a uniform main battery into a coherent new standard, making her a conservative engineering leap with revolutionary consequences.