Reflex defense, reflex save. Mechanically nearly identical. The only variation being who's rolling the dice. That and evasion being much more available in slightly earlier editions of D&D for avoiding those pesky dragon breath weapons. You can see a wonderful example of a dragon breath weapon in the above poster. I've used a few dragons against my players in my time as a GM. The most memorable fight didn't have the dragon using its breath weapon much at all. This was due to the players engaging it from the backs of hippogriffs. They were suitable cowed when it first showed up over the town they had made their home base. Fortunately not cowed so far as to run screaming for the hills. Two of them nearly died in the fight and a grand time was had by all. Except the townsfolk who had their houses crushed by the falling body of the deceased dragon, but that was inconsequential.