Domain Authority is a search engine ranking score (SERS) developed by SEO software company Moz, which estimates how well your website is working and provides a rating score from 1-100. Higher the score, higher is the ranking of your website in search engines and more organic traffic your website will get.
Whereas Page authority is scored using logarithms to rank each page. Improving your score significantly can be easy or difficult depending on your starting point. If your score is low, in the 20s, it will be easier to grow that to the 30s than it would be to grow a page from the 60s to 70s. Getting better results when you’ve hit greater than 75 on your score will be slow and difficult.
Domain Authority is completely different from page authority. Though Page Authority also works on the same metric and algorithm but page rank analyses and rank any individual webpage, whereas DA analyses the whole domain. Moreover, a good DA depends on the domain authority of the sites you are competing with.
Rahul Gupta