Col 1:15-17
"He is the image of the invisible God, the firstborn of all creation. For by him all things were created, in heaven and on earth, visible and invisible... all things were created through him and for him. And he is before all things, and in him all things hold together."
Eikon tou theou — image of God: not a copy, but a perfect representation. Prototokos pases ktiseos — firstborn of all creation: not the first created, but the sovereign over all creation (cf. Ps 89:27 where 'firstborn' = sovereign). Christ is the cause (di autou), the sustainer (en auto synesteken), and the goal (eis auton) of all creation.
Col 1:18-20
"And he is the head of the body, the church. He is the beginning, the firstborn from the dead, that in everything he might be preeminent. For in him all the fullness was pleased to dwell, and through him to reconcile to himself all things, whether on earth or in heaven, making peace by the blood of his cross."
Christ is the head of the church and the firstborn from the dead — the resurrection as new creation. The pleroma (fullness) dwells in Christ — against the Gnostics who divided the divine into emanations. Peace was made 'by the blood of his cross' — the reconciliation is cosmic.