On various websites in the U.S. I see a distinction being made between personal holiday and vacation. What is the difference? Some examples:
Wisconsin Jobs lists Annual Vacation Hours Schedules and states that additionally, the State of Wisconsin provides 4 1/2 days of personal holiday time..
California State University lists An employee is entitled to one (1) Personal Holiday, and Vacation is an accrued benefit which provides paid time off.
University of Iowa HRM writes that Members of the University staff are eligible for 11 paid holidays a year -- two personal holidays that accrue and are taken as vacation, and [list of nine holidays such as Christmas, New Year, etc.], then on this page they list details about vacation (but not holidays).
What are the definitions of (personal) holiday, (personal) vacation? Are those subsets of paid time off?