The 2342 is a 4 megapixel (MP) camera as opposed to the 2332 which is a 3MP camera.
The aspect ratio of the 2332 is about 4:3 (like old TVs before HD), whereas the the 2342 will give you a picture about a 16:9 ratio (widescreen, HD).
I am by no means an expert here, but from what I have picked up on these forums, and as the owner of many of these Hik turrets, the sensor on the 2342 is much better at night than on the 2332. Better low light/nighttime picture.
However you might not want either of these cams:
Spend a little more money and get the new DS-2CD2335. From the reports on this forum, it's a 3MP Hik turret cam with much much better low light/nightime ability than either cam you mentioned. Wont cost you that much more either. There is a thread here in this forum with peoples experiences with this new cam. I find myself wanting to pick one of these up as soon as I can.
Best wishes!