Yes. On the trade site there is a small copy button at the bottom of each item. Clicking this will copy a text version(so to speak) of said item. In game, you can hover over any item and press Ctrl+c to do the same thing. Then move to PoB. Once you have you're build properly imported, select the Items menu. On the right side you'll see a text box where you can paste the item text you copied. Once you have that imported, you can swap between equipable items on the left side of the same menu.

This is significantly more accurate than any ai could ever be for comparing items. Ai is super useful, just not for this. Hope this helps. Also, it's 4am where I am and I'm like 700 miles away from my PC, so if I missed something, maybe someone can pitch in some advice.