I have not used 530 of course, but if I understood you cannot navigate to address or POI (not saved location). I do not know how to do it via garmin-connect also.
On roam you can click “take me to” and select location on map, which can be done on 830 only. take me to address can be done from phone (not like 830).
I agree that if_you_do_not_have_phone than roam is the same like 530. But if you have it - its not the same (but phone does not add much value to 530)