The former does not require consent. The latter does.
For example, the CAN-SPAM act requires the words "SEXUALLY EXPLICIT" to accompany messages with sexual/adult content. A tracking cookie's name can simply have the word "tracking" in it, which would trigger a browser to throw up a consent pop-up. A long, useless message from the site about why the user should click it could be provided to the user in a number of ways. The law doesn't even have to specify that