The term 'pre-war' refers to the Second World War. These high rise buildings were built after 1900 and before 1940. They are usually between 10 and 20 stories high. During these years unemployment was very high and construction workers tried to make their jobs last. That had the effect that pre-war buildings are built in a very sturdy fashion! The apartments are quiet and most have - for NY standards - ample space. A 1 BR apartment will have a 'real' bedroom (as opposed to townhouse apartments, where the bedroom is very often a cut up piece of a larger room) and you will have a nice hallway and large closets.
Some pre-war buildings have doormen or used to have elevator men. The really desirable ones, like Bing and Bing buildings have become exclusive COOPs and it's very unlikely, that the COOP board (the owner association) allows subletting - as in a vacation rental!
You will pay more for an apartment in a pre-war than in a townhouse, but you will get more space, privacy and an elevator.