IVF insurance coverage question...

We were told that our insurance will cover most of our IVF treatments since we have been trying so long and nothing has worked but first we will need to meet out deductible, and then insurance will pay anything after that (except co pays and meds).

Does anyone know if they mean having to meet your overall deductible OR reaching your out of pocket maximum? Not sure what the difference is between the two, but there is a huge difference in amount of money.