Registration and activation are completely different.
Activation is a mandatory process that requires the software to connect to Adobe servers via the Internet and associates the products you buy from Adobe with the computers on which you use those products. Activation helps protect your computers and environments from malicious code by verifying that you have genuine Adobe software.
Registration is an optional process that gives you access to a wide range of benefits and options, including access to support, notification of product updates, newsletters, special offers, and invitations to Adobe events.