What is the difference between open access and open archive?
As Elsevier uses these terms, "open access" means an article is free to access as soon as it is published. "Open archive" means an article is published in a journal that makes articles available for free after some embargo period (not immediately when it is published).

More on Open Archive:


  Elsevier enables subscribers and the general public to have free access to archived material in 98 Elsevier journals... Articles featured in the archives are free for everyone to read and download and are made available after an embargo period.