To understand why nobody can agree on what enhancements actually are, you have to recognise that the term is in itself academically divisive. There is great variability in the literature as to what it may refer, ranging from the relatively narrow scope given by a European Parliament Science and Technology Options Assessment (EP STOA)-
“a modification aimed at improving individual human performance and brought about by [specifically] science-based or technology-based interventions in the human body… Excluded… are improvements of human performance which are realised by the use of devices which are not implanted or not robustly fixed to the body”
“an intervention- a human action of any kind- that improves some capacity (or characteristic) that normal human beings ordinarily have or, more radically, that produces a new one.”
Those seem pretty different!