The top section screws off the V3 to expose the ego threading, not so on V2. The screen is a little nicer on the V3 than on the V2, but not a game changer. The V3 only has NO2 mode, the V2 has both NO1 and NO2, but NO2 is what all Vamo users recommend to set their V2s on. The V3 middle battery section unscrews from the button/screen area, this part is glued in place on the V2 (makes sense to have all the parts threaded and not glued, but it hasn't became unglued on my V2). Pretty sure the 510 threading can be shabby on both, but it's a coin toss. I think that about covers it and I too am not a fan of the swirls on the V3.
You might also consider buying an Innokin SVD for $5 more than the V2 or V3, although I'm not sure about the NO1, NO2 settings on that device, or really what those settings do exactly (NO2, I think, makes your voltage/wattage more accurate, where NO1 is like an average, something like that anyways).