Mitch:
Go to both fiestas!! You will clearly see the difference of classes, positions, etc. I love the one in Arpar, that's the one most similar to the one in Llamellin. They have Pallas, Pizarros -- even "danzantes," which is not a traditional dance from December but rather from September in Llamellin, but I guess because Dececember is when everyone gathers in Lima, they thought everything was possible in one fiesta.