Import/Export

Paris needs from NY:

-Cold-brewed iced coffee. (What I've attempted with the French press here half-works, but what I'd give for some Think or Third Rail.)
-Garlic scapes.
-Air-conditioned public transportation.
-Real sales. None of this 20% off nonsense.
-Shake Shack.
-Places it's possible to sit and read a book with maybe a coffee and a pastry around 4pm. This would seem to be the very essence of what Paris is about, but cafés at that hour are in fact intended to sit with six friends in, consuming only beverages. Fun, but not conducive to dissertation writing. There are salons de thé, but these seem to be places where, for the low low price of 24 euros, I'd be in for far more than, say, an espresso and a macaron.
-Dermatologists. It's not permitted here to ride the Metro if you're not currently picking at a very active skin disease of some kind. I'm not a dermatologist, but if even I can think of roughly what creams need to be prescribed in these situations, imagine what a professional could do.

NY needs from Paris:

-Signs on the subway with when the next and the following train will arrive.
-Cheesewinepastry, obviously.
-Beautiful buildings everywhere.
-The Seine. (Sorry, Hudson, East River.)
-Creative alternatives to leggings-as-pants. This would be the weather for super-casual attire, so the fact that I'm not seeing leggings-as-pants must mean it's not a trend here.
-Women with their original noses. Or just generally, women who, though rich and attentive to appearance, do not appear to have accounted for every square-inch of their bodies, the way the women of the Upper East Side or Tribeca have, with some combination of exercise, diet, and surgery. Here, I get the sense that women just slap on a (placebo) cellulite cream and focus on what really matters, such as clothing and accessories. That said, the cosmetic alteration one does see here is typically over-the-top - cartoon inflated lips, breasts, and so forth. But it's unusual.

But overall, these two cities are so similar, it's easy to forget which one's which. Crowded subways, tiny apartments, a skinny and racially diverse populace, French-speaking shoe-shoppers, Uniqlo bags everywhere (and no, I have not - yet - visited Paris's flagship), the potential to do or buy virtually anything, the knowledge that there are always streets you haven't seen... In terms of compare/contrast, I think this may be all you're getting for a while.