Identity and selfhood are closely related but distinct concepts.
Identity describes continuity. It allows us to recognise that a living system remains the same individual across time despite growth, development, learning, ageing, and other forms of change.
Selfhood explains continuity. Within APSI, selfhood is the persistent integrative organisation through which living systems maintain continuity despite continual material, developmental, cognitive, and experiential change.
The distinction is important because recognising continuity is not the same as explaining it. To identify a tree as the same organism throughout its life, or a person as the same individual across decades of change, is to describe continuity. APSI asks a deeper question: how is such continuity maintained despite continual transformation?
Identity records the persistence of a living system. Selfhood explains the organisational basis of that persistence.
In APSI, identity refers to the recognition of continuity, whereas selfhood refers to the persistent organisation that makes such continuity possible.