The second reason it can be confusing is the industry uses “resilience” in two completely separate ways when they talk about polyfoam. The Polyurethane Foam Association provides the following definitions:
Resilience – An indicator of the surface elasticity or “springiness” of polyurethane foam. It is measured by dropping a standard steel ball onto the FPF cushion from a given height and measuring what percentage the ball rebounds.
High Resilience (HR) polyurethane foam – High Resilience polyurethane foam have a high support factor and greater surface resilience than conventional polyurethane foams and are defined in ASTM D3770. High resilience (HR) polyurethane foam has a less uniform (more random) cell structure, different from conventional products. The different cell structure helps add support, comfort, and resilience or bounce.
In one case, resilience only refers to bounce while in the other it refers to bounce and support. It makes a difference if they refer to it as “resilient,” “high-resilience (HR),” or highly resilient. “Highly resilient” may refer only to bounce and not to support.