A tracked link is used to track and report on users who follow the link to a product page on an external site. The tracking ends here.
A clickstream link also tracks and reports on users who follow a link to a product page on an external site or landing page, but a clickstream link then follows the sequence of clicks that are performed by the users while they browse a website or an landing page.
While a tracked link shows only as a click in reporting, a clickstream shows two places in your reporting. For the clickstream type, you see both clicks and clickstream. The clicks are the actions that are performed when a recipient clicks a clickstream link in the email. The clickstream reporting includes the sequence of clicks the recipient took after they opened the destination website or landing page.