I'm not familiar with either ball other than the fact the Supernova is a solid while the XP is a pearl cover.
Based on that and relating to other similar type covers, I would think that the reason for the different reactions, most likely, would be that the volume of oil on the lanes was too light for the 'nova. It was burning up through the heads and mids and lost its side rotation before hitting the dry.
The Xp with its pearl cover and its lower friction in the lighter oil was able to maintain its side rotation through the oil and still give you a good reaction off the dry.
--------------------
If Snoopy and the Red Baron can get along for the holiday, why can't we?
Whichever holiday(s) you choose to celebrate,
May they be filled with Peace, Joy and Happiness for all.