The thing that sets HathiTrust apart from Google Books and other large digital library projects is the fact that a key element of the project is a focus on the preservation of digitized information resources. This element of their mission is integral to their project as a whole. While other large-scale digital library projects are also concerned with providing widespread access to digitized materials, few make the aspect of preservation apparent in their stated missions (although some others certainly do, like the Internet Archive). In particular, Google Books makes no mention whatsoever of preservation on the history section of its website. It is the same case with Project Gutenberg. Alternatively, the HathiTrust makes multiple references to its preservation focus, both in the history section of its website as well as in its actual mission statement. As Heather Christenson stated in her article, “At the heart of HathiTrust is a shared secure digital repository owned and operated by a partnership of major research libraries. The repository is best known as a means of preserving digital materials created via large-scale digitization projects.” This is a great point – that the “heart” of the project is its preservation aspect. Christenson later states what may be the most important point: “Although Google and the Internet Archive both maintain and provide access to large amounts of data as a matter of course, neither organization is formally committed to digital preservation of digitized books over time.” Of course, it can be argued that all digital library projects are archival simply by their nature – but the point above in particular helps to articulate the fundamental difference between HathiTrust and other digital library projects.
As for the relationship between HathiTrust and DPLA, I think the two projects will compliment each other well. The fact that each one is geared towards certain users (public vs. academic) is a good thing. By focusing on the needs of different types of users, each collection can provide the most focused and therefore relevant resources to their patrons. It’s an exciting thought that future generations of users will have access to numerous types of digital collections over the course of their entire lives.