NGK Iridium IX vs Laser Iridium — what's the difference?

Across r/MechanicAdvice and r/subaruimpreza threads, the consensus is that Iridium IX is NGK's performance-oriented line with a fine-wire iridium center electrode, while Laser Iridium adds a platinum ground electrode pad for longer life and is more commonly specified as OEM. Laser Iridium typically lasts longer; Iridium IX is often a step up in ignitability for tuned or higher-output applications.