difference between behavioral and structural
If you just have a netlist file, I think it cannot be determined whether It is behavioral or structural. The reason is both HDL entry and schematic entry can generate netlist file.
If it is schematic entry, it will be structural.
If it is HDL entry, it cannot be determined whether it is behavioral or structural unless you see the details of the netlist file.
As I know, some netlist file will describe structural. Then maybe the design is structural.
If I am wrong, please correct me.