I have one of each, both a little less than two years old. Metalwork , I do not see any difference, I do like the beech stock on the IZH better than the red black laminate, which I ended up replacing with a set of custom Rink grips. First the little pad on the cocking lever split, when I was taking it out of my storage case, then I noticed a spot on the main body groove where the palmrest is adjusted had split.
There was plenty of wood on the IZH grips which are rather blocky, but I found that to be an advantage, Over a couple of weeks I rounded sharp edges and created some finger grooves where my fingers wrap around the grip, I went slow and made it fit my hand perfectly.
I got the AV from Pyramid air and the IZH from I think Canada air gun before they got scarce and prices ran up. They fit so well and shoot so good I would not take $1000 for either, basically two of eight out of about 20 that I would not sell at all.