West Hampstead (the settlement, not just one of the stations, almost) was originally "West End". As distinct from the West End of London. I suppose the implication is that it was the West End of Hampstead, but more recently the term seems to be used often as a way of saying "Kilburn" (which itself has West and South variants, but nor North or East), as it apparently sounds more prestigious. What I find slightly odd round there is that whereas West End Green is a focal point of what is now West Hampstead, South End Green is some miles (in a north-easterly direction) from what we now call South Hampstead. Arguably the location of the Heath rules out the possibility of North or East Hampsteads....