I can answer your question in specific, but its depends on may factors so in general i can say: The stacking-fault energy (SFE) modifies the ability of a dislocation in a crystal to glide onto an intersecting slip plane. For Al its 160-200 mJ/m2 , and the copper less SFE 70-78 mJ/m2. Therefore, the Aluminum much ductile than Copper without cold working or alloying elements.

Electrical and themal conductivities of Cu are higher than those of Al, and this fact is not related to ductility but to electronic structure. The only relationship between conductivity and ductility is the following. Introducing defects into the metal structure will produce hardening and also scattering for electrons and phonons, hence lower electrical and themal conductivities. Thus, for a given metal, the harder it is, the lower its conductivity. This is a general trend, and exceptions might exist.

Alain

I guess it might be more related to the dopped composition, regarding to the pure metal, I believe the Copper is better in ductile.