I don't think he was asking about the different levels but more of as in how the pvp level system works. Here's how it works. Your pvp rank has nothing to do with your honorable kills and there is no set number for how much honor you need to obtain a certain rank (i think there is a minimum for the higher ranks though). The ranks go from 1-14. How many people can be a rank depend on your server size. If you have a bigger server more people can be a certain rank because it's done by percentages. Only 0.1% of players can be rank 14. So if you had 1000 players only one person could be rank 14. Also honor from killing another player isn't just determined by if you do it yourself and the level difference. It's based on their level compared to yours. Their PvP rank compared to yours. And if you you were assisted in your kill.
This goes a bit more in-depth
http://www.worldofwarcraft.com/pvp/pvp- ... part2.html