In a new episode of #AskGooglebot, Google employee John Mueller explained the difference between absolute and relative URLs, as well as whether the search engine has a format preference – in terms of crawling and indexing.
According to Mueller, an absolute URL is the full address of the page you are linking to. This is analogous to giving a person the complete address of the place they are trying to find.
A relative URL is the location associated with a specific page when the starting page is taken as the starting point. In other words, this is where you are now. A relative URL is an incomplete page address.
When implemented correctly, both options denote the same place, notes NIX Solutions.
Site owners may prefer one or the other. That said, it doesn’t matter to Google which one is used: both are acceptable.
Google treats both options the same way. It is also possible to use different URL formats on the same site. For a search engine, there are no significant differences between them.