This is the same distinction as Russellianism vs. Fregeanism, except applied specifically to proper names. I think in the Philpapers survey, this question replaced the Russellianism vs. Fregeanism one.

Fregean: The meaning of a proper name is a way of conceiving of its bearer. Different names for the same bearer may be associated with different ways of conceiving, and thus have different meanings. For instance, "Superman" and "Clark Kent" have different meanings.

Millian: The meaning of a proper name is its bearer. The meanings of "Superman" and "Clark Kent" are identical.