What is the difference between Bonnell springs and pocket springs?

In a Bonnell spring core, the springs are interconnected, so the mattress moves as a single unit. In a pocket spring core, each spring sits in its own pocket and responds individually to localised pressure. That gives you more precise pressure distribution, far less movement transfer to your partner and better shape retention over time. Bonnell springs are cheaper to produce, which is why they are found in many entry-level mattresses. Revor works exclusively with thermally hardened pocket springs.