What is the difference between a dean at a university and a dean at a high school, if any?

"In academic administration, a dean is a person with significant authority."

The biggest difference would probably lie in the age difference of the students...each student body requiring a bit of a different approach.

https://en.wikipedia.org/wiki/Dean_%28education%29

Dean at a high school is an appointed position, but does not have any authority over the school, that is left for the schoolmaster or principal.

Deans at colleges and universities are also appointed, most often from the ranks of the faculty. However, a dean in higher education is generally the chief administrative officer of some portion of the institution -- the College of Arts and Sciences, the Law School, the Graduate School, etc.

As zbeck's site mentions, a dean at a high school whether public or private is more likely to handle disciplinary issues. The dean of students at the high school I attended also oversaw extracurricular activities, academic problems and probation, and notified parents regarding student illnesses and injuries.

Having never attended either high school or college, I wouldn't know from firsthand experience, but any desk reference or online dictionary could easily answer this question.

Main Entry:dean
Pronunciation:*d*n
Function:noun
Etymology:Middle English deen, from Anglo-French deen, deien, from Late Latin decanus chief of ten, from Greek dekanos, from deka ten — more at TEN
Date:13th century

1 a : the head of the chapter of a collegiate or cathedral church b : a Roman Catholic priest who supervises one district of a diocese
2 a : the head of a division, faculty, college, or school of a university b : a college or secondary school administrator in charge of counseling and disciplining students
3 : DOYEN 1
–dean intransitive verb
–dean£ship -*ship noun

In junior high it was the person you got sent to if you misbehaved. Our dean of girls was aptly named "Mrs. Cannon."