I don’t know, they just told me that if you miss 2 pills back to back, you’re unprotected. I honestly don’t know, I recommend you talk to their chat line! I am just sharing what they told me! I honestly don’t know the diff! Don’t worry girl, I have been on the combo pill for 2 years and I don’t take it at the same time everyday, one day I’ll take it in the AM and the next PM! I asked them if that was ok and they told me yes but as long as you take one everyday