DLCs vs IAPs

Can someone provide some clarity on how Meta differentiates between DLCs and IAPs? I had always thought DLCs = expansion packs, extra levels, etc and IAPs were like in-game currency, skins, etc.  However, the way Oculus' documentation describes it makes it sound like DLCs are additional asset files that can (have to be?) purchased in the Oculus store, while IAPs are any purchasable item (can be a skin, can also be an expansion pack) that was packaged with your build the last time you uploaded it? Can you even purchase an IAP from the Oculus store? Or is the difference that DLCs are in the store b/c they're an additional asset file independently shipped, while an IAP is already uploaded along with the app, so you don't need to upload any additional files? If this is the case, then why do we need/have the option to create an "Add-On" in the Oculus Developer Hub for IAPs, and not have them shown in-store? Is that strictly just to standardize how payments in general work on Oculus' end? Any clarification would be super helpful. Thanks!