Jelly Bean only has 3 API levels covered, 16-18 which correspond to 4.1.x, 4.2.x and 4.3.x. If you're on any 4.2.x you're on API level 17. So the Note 2 is currently two levels behind (with many versions in between) and 19 is still at least a month out.
The Verizon GNex I'm not sure what version Verizon is on, mine's been on 4.3 since about 4 hours after it was announced thanks to devs.
A good question to ask is, "what features or stability improvements, etc. will 4.3 bring to the Note 2 that 4.2 wouldn't?", etc. When you're on such feaure heavy devices, pure android updates aren't often bringing a lot.