My Dentist Gave Me A Temporary Upper Denture When My

My dentist gave me a temporary upper denture when my 2 remaining upper front teeth were removed. Years prior I had all but these two teeth removed and a bridge was affixed to the two remaining teeth. So, when my two remaining teeth were removed the bridge couldn't stay as there were no teeth to affix it to thus the dentist gave me a temporary full upper denture. I still need to get permanent dentures since the immediate ones are just temporary. My dentists billing clerk has told me that the denture wasn't an immediate complete denture but an interim complete denture (the first is covered by insurance and second isn't). The billing office says that an immediate complete denture is a permanent complete denture. I understand that an immediate denture is given immediately after teeth are extracted like in my case but I can't figure out what an interim denture is or rather the difference between an immediate and interim denture. My guess is an interim is one that would be given if someone's "permanent" denture breaks or is lost whereas an immediate denture is one that's given immediately after tooth extraction. It seems that both are really temporary dentures. Can someone explain the difference between and immediate complete denture and an interim denture? Also, is an immediate denture a "permanent" denture? Thanks