The main difference between Redirect links and other link types is that these links always point to your Post Affiliate Pro URL and include the affiliate variables, e.g.:
https://URL_TO_PostAffiliatePro/scripts/click.php?a_aid=refid&a_bid=73d672s1
The click.php script creates a browser cookie in visitor's browser, registers a click to an affiliate with the particular refid and registers a per click commission (if defined) computed based on the campaign to which the banner identified by a_bid variable belongs. When the click is saved and browser cookie created the visitor is redirected to the Destination URL defined for this link, e.g. https://mywebsite.com/. So when you click on a link like
https://URL_TO_PostAffiliatePro/scripts/click.php?a_aid=refid&a_bid=73d672s1
The click.php script creates a browser cookie in visitor's browser, registers a click to an affiliate with the particular refid and registers a per click commission (if defined) computed based on the campaign to which the banner identified by a_bid variable belongs. When the click is saved and browser cookie created the visitor is redirected to the Destination URL defined for this link, e.g. https://mywebsite.com/. So when you click on a link like
https://URL_TO_PostAffiliatePro/scripts/click.php?a_aid=refid&a_bid=73d672s1
you will immediately get redirected to the Destination URL (target URL) defined in the banner with ID represented by the value of a_bid in the link you have clicked - https://mywebsite.com/.