The reason why DA and PA are often different is because they measure different aspects of a website's authority and influence:
Domain Authority (DA) measures the overall authority of a website's domain. It gives an indication of how well a website is likely to perform in search engine rankings compared to other websites. DA takes into account the quality and quantity of backlinks pointing to the entire domain, as well as other factors.
Page Authority (PA), on the other hand, measures the authority of individual pages within a website. It evaluates the likelihood of a specific page ranking well in search engine results. PA is influenced by factors such as the number and quality of backlinks pointing to that particular page, the content relevance, and the internal linking structure.
Since DA and PA consider different sets of factors and are calculated separately, it's common for them to be different for the same website. For example, a website might have a high DA due to strong backlink profiles pointing to its domain, but individual pages within that website may have varying levels of authority (PA) depending on their specific content and backlink profiles.
In summary, DA and PA are complementary metrics that provide insights into different aspects of a website's authority and SEO performance.