How to switch ROM? From Lollipop back to stock, help!

I am running stock right now (JB 4.2.2) and I am planning to flash a Lollipop ROM (AICP 10). If I create a backup (for my stock ROM) at TWRP and did the needed measures to flash the Lollipop ROM and was successful however I want to return to stock ROM. Do I just have to factory reset and restore my stock ROM backup to have a stock ROM again? Sorry for this noob question.