MozRank is based on an exponential scale between 0 to 10, based on the number and quality of the other linked pages to them. This can refer to a particular page or an entire website.
Moz Domain Authority is based on an exponential scale between 0 to 100. It is calculated using MozRank, MozTrust, linking root domains, number of total links and dozens of other factors. As the name implies, this metric can only refer to an entire website.