Oh, yes. Sorry. They are different parts of Manhattan. Roughly, though there are specific (and to the north, different) streets bordering them, the UES, for example, is the area to the east of Central Park and the UWS, that to the west. It is 59th St. that is the southern border to all three, and this building is two blocks south, on 57th.
The next little chunk of the City to the south is ‘Midtown’, and on the eastern side of the island, it is Midtown East. Though there are also some smaller neighborhoods within those larger areas, and this building is also in a smaller neighborhood called Sutton Place.
Manhattan is only one of the five larger ‘boroughs’ of the City overall.
While we're at it, I hope you'll answer my other question: New Yorkers refer to numbered street intersections, such as "3rd and 21st," without specifying which are Avenues and which are Streets. I'm assuming Avenues run in one direction and Streets in the other. The question is: what convention are they all using, which is unstated but universally understood? My assumption is that it's "Avenues, then Streets," because that's alphabetical.