Rendering beef fat or pork fat yields tallow or lard and cracklings. Does anyone know what the structural difference between the crunchy cracklings and heated liquid fat is reflecting? Is it a more saturated situation? Are there going to be less PUFAs in the pork cracklings than in the rendered lard? The pork fat is from hogs fed a varied diet though all appear to get fed some grain now, some more than others.
Maybe I'm misreading your question, but you also get cracklings when you render beef into tallow. I think if you've left it in heat long enough, there shouldn't be much fat left in the cracklings. I believe they are mostly protein and minerals. This document seems to have a lot of relevant information:
How to Get Animal Fat 8 Answers
Tallow, Lard and Schmaltz Battle Royale 5 Answers
nutrition: Lard VS Tallow 5 Answers