"Specs" tab on the site explains the difference in the series........
The same brass base metal that we've been making for 2 years only now we've improved our Duraplat3-dâ„¢ plating process to produce the hardest surface finish possible (almost 70 Rockwell). These are still a perfect replacement for OEM nozzles and great for all around printing.
Made from the toughest alloy 7075 aircraft aluminum. A step up from the Elite series, these offer 60% more heat transfer than brass nozzles and better wear resistance.
Manufactured using heat treated A2 tool steel. With 50% better heat transfer than stainless steel nozzles, these are the clear cut choice for printing the harshest and most abrasive filaments like carbon fiber and metallics."
Going to try the "Apollo" series....... -David