The square cap gets a better re-sale price. The specimen is just a bullion coin in a velvet lined case instead of a cap with an added bit of paper that means squat (at the moment) but both seem to fetch more than the Proof versions for some reason?
I purchased 1990 -1995 proofs cheaper than 1990-1995 square cap bullion coins recently, it seems to be a trend to prefer or demand more for the square cap bullion than both specimen and proof.
One have Lacquered the other doesn't, hence Patina on the rim
Depend how you stacked them. Some prefer to put in the tube , other prefer to stack em in a box.
I stacked both Tubes= Round caps and Boxes= Square caps.