Rashi on Genesis
אלה אלופי בני עשו THESE WERE CHIEFTAINS OF THE SONS OF ESAU — Heads of families.
Rashbam on Genesis
All the Alufim mentioned in this chapter are heads of cities of clans. I believe that the אלוף קרח mentioned in this verse as one of the sons of Eliphaz is identical with the תמנע mentioned in Chronicles as a son of Eliphaz, (compare verse 12) whereas the קרח, mentioned in verse 18 here as the son of Oholovimah, is a different person by the same name.
Siftei Chakhamim
Heads of families. Rashi is saying they were leaders and heads, each over a different family, but not that the families were formed by them.