Recent debris disk observations, most notably the ARKS ALMA large program, have imaged the detailed structure of planetesimal belts in a substantial number of mature exoplanetary systems. These observations have provided new insight into the planetesimal formation outcome, enabling a direct demographic comparison with the formation environment in protoplanetary disks. This talk will address three questions: (1) what kind of substructures are seen in the ARKS program (e.g., rings and gaps, halos, non-Gaussian vertical profiles, asymmetries), (2) how radial substructures in debris disks dynamically relate to those seen in protoplanetary disks (e.g., viscous diffusion, dust trap vs. disk clearing formation channels), and (3) what these structures reveal about the outcome of planet formation and ongoing evolution (e.g., disk mass, outer giant planet demographics, planet migration).
