ok. I'm not sure if they have updated any of the L2 guns so this is based on info from the past, but I think its still the same.
The lvl 100 guns have a slightly longer range than the lvl 110 but do less damage. The lvl 100 guns weigh less allowing for more armour or speed depending on which you go for (I suggest armour but only if you can fully armour it). I agree with barrel when he says DONT use the lvl 110 guns. If used properly the small range difference can make a big difference and the damage output doesnt make that much of a difference due to the massive amount of damage that the L2 does anyway.
A little note about hitting through QV armour:
Neither of these guns can without AP. You may get a couple of lucky shots but generally you will not do much. your best chance when fighting a QV would be to change to AP shells, smoke and rush but make sure you can get away if you take a bad hit from the QV (because it will definitely hurt). Or just wait for other people on your team.