Although I would expect the latter to be a pointer to the first, i can't see the Epics I have created through "Create Issue" in the pull down of the Epic/Theme field (Which can optionally be shown inside an issue in edit mode).
My current conclusion is that they are not the same thing, and that the similar name is just a confusion. I assume that the Epic/Theme field is more like a free label, and is not shown in the Issues table as an Epic created via "Create Issue".
Is my understanding correct? do we have here 2 different Epic entities with no correlation between them?