The 'adoption' we wait for and the 'redemption of our bodies' seem like two things, but they're deeply connected.
Paul presents the final 'adoption as sons' and the 'redemption of our bodies' as intertwined aspects of the same future event. They aren't two separate hopes, but two facets of our complete glorification.
Our current adoption is a spiritual reality, a divine declaration that we are God's children. However, this adoption isn't fully visible or experienced in its ultimate form yet. The grand, public 'coming out party' for God's sons and daughters is yet to happen.
This final adoption is intrinsically linked to the redemption of our bodies. When our bodies are resurrected, transformed, and freed from mortality and corruption, we will be fully revealed as God's sons and daughters, complete in Him. It's when the entire person—body, soul, and spirit—is brought into the full, manifest liberty and glory that belongs to children of the Heavenly Father.
Think of it like this: the legal declaration of adoption happens now, but the full inheritance and public recognition, tied to our resurrected bodies, happen at the end.