Is Harvard Extension specifically, Harvard College’s Division of Continuing Education?
HES is one part of DCE; the 2 are not the same thing.
Harvard College Division of Continuing Education is the umbrella organization for various divisions of continuing education, with HES being one of them. See: http://www.dce.harvard.edu.
There are many other threads on the Harvard Forum about HES. See: http://talk.collegeconfidential.com/harvard-university/1789406-harvard-extension-school.html