Actually I can understand it myself. Priests are more intrinsically attuned to ways and the flows of their divine powers. They have a deeper understanding of what it can do. Paladins by contrast are much more martial class. They eschew the deeper meanings of the Holy Light in favor of a more militant and martial mindset. A good contrast in this is look at Velen as oppose to say Tyrion. Priests spend their time in meditation, contemplation and reflection of the mysteries of the Holy Light. While Paladins train with weapons and such.