The difference between registration and declaration of a place of residence

The Migration Service of the Dnipropetrovsk region explained the difference between registration and declaration of a place of residence. A declaration is made electronically through the Unified State Web Portal for privately owned housing or dormitories under certain conditions. Registration, on the other hand, is done by submitting a paper application to the registration authority or through an administrative service center for housing of any form of ownership. Does this mean that if I live in an apartment owned by my family, I must declare my place of residence, and if I rent another apartment, I must register it?