Welcome to irv2 gun wiz!,
Not sure if I fully understand your question, but will do the best I can to answer.
The 12 volt system will only operate the 12 volt lights, 12v accessories, water pump and 12 volt fridge if equipped.
The 30 amp system will only operate when plugged into shore power. You can operate most household appliances and electronics with this system. If your pop up unit has a voltage converter it will power all the 12 volt items and charge the battery when plugged into 120v shore power. Some people use generators while camping so both 12v and 120v systems will operate.
Hope this helps,
'98 Gulf Stream Sunsport 325, 7.5L Banks Power Pack, Koni FSD's, Air Bags, ReadyBrute Elite,
2000 Honda Accord