It is greener to download music than to acquire hard copy CDs of the same music through analog methods. An article in earth2tech.com gives background and details. One supposes the principles in the report would apply to many other changes from hard copy acquisition to the digital download sort. Here is some of the earth2tech discussion:
. . . The research compares an album published on a CD and shipped to a brick-n-mortar retail outlet, an album published on a CD and bought via e-commerce (both shipped via truck and air), an album downloaded and used digitally, and an album downloaded and burned to a CD used with and without a jewel case (these guys were thorough).
The findings are important because despite the growing concern over the increasing amount of energy used by the Internet, this proves that the Internet can be a substantial source for dematerialization — replacing atoms with digital bits, reducing goods created and reducing carbon emissions. . . .