The short answer: Soft gel, rubber gel and builder gel are all light-cured gels: liquid acrylates that harden under a UV or LED lamp. (Builder gel is also called hard gel; most nail pros, us included, use the names interchangeably.) What separates them is cross-linking, or how tightly the molecules lock together once cured.

• Soft gel (gel polish and soft gel extensions) is the color layer. It's flexible and glossy.

• Rubber gel (rubber base) is a thicker, bendy base that cushions thin or soft nails and helps a manicure stay put.

• Builder gel, a.k.a. hard gel, has the tightest network. It's thick, rigid and strong, made to reinforce and sculpt, and it's filed off rather than dissolved.

Think silk, neoprene and armor. Same fiber, very different weave.