As you level up in PVP, is it easier to kill lower leveled people, or does it only have to do with..

It is all dependent on your weapon's damage vs your targets gear rating. Also a headshot will give you the full damage rating for your weapon, where as a body shot will only dish out 50%.

i.e. if your sniper rifle has damage of 3000 but your target has gear rating of 9000 it will take 3 headshots or 6 body shots to kill.

Gear rating and damage have nothing to do with your opponents level, Raven, Wolf, Bear, Lion or Skull.

The token's you earn in PvP determine your level. So the more you play PvP, the higher your level. So a "Copper Raven" could potentially have the best gun in the game and great armour.

As you move up, everyone else does. How you strategize your game play is the type of player you become. For example; Im a WD weapon damage player, i invest in WD. I only have GR 770, but my tier 21 rifle is at 8k WD plus. You can take me out with one shot, but I can take out GR 20k plus players with 1 dome shot, 2 at the most. The reasoning, I score higher, more BlueSkulls, move up in rank faster. What approach will you take is the question?