Hi Kevin,
ListGetDataCfg is for reading elements from list object which you can define directly in IRD. It is the List objects icon in the left pane in the IRD folder "Routing Desing" or you can find it also in the menu View. Each list object can have set of items and each item can have set of KVPs. So plenty of room for configuration data.
Function GetConfigOption is reading options defined directly in annex table of particular configuration object in CME(usually in section __ROUTER__ just to have it nicely organized. You can use Routing Points, Tenant, TServer, Routing server ...etc. . Usually it is used at the RoutingPoint annex table because it allows you to define the same option for every Routing point with different values as the function is firstly looking for the option at the RP where the strategy is loaded. So you can have different parameters for the same strategy loaded on different RP. Then if not found it goes up in the objects hierarchy for Switch/Tenant/URS/Tserver (or probably there is no such logic and just simply takes the first option found in CME database). This works with parameter "StartFromCDN" (current dn). There are other parameters which specifies where this function should look in the first place such as "StartFromRouter", StartFromTenant, StartFromTServer ...
Hopefully it helps.
Cheers,
e.