Good question!!!! How can I explain it in words? Weight is a major factor the diameter of the twine is another. Without haveing them side by side to compare, to a person who is not familar with them it is bloody hard to say the least. If you were buying a sheet of the net one way would be to pick up the wrapped sheet in the middle, with a 4z net the ends of the net should bend and be almost touching beneath your hand a 6z sheet would not bend that far. However, that is not a foolproof method as some 4z's have a heavier coating of bonding and that makes the twine stiffer. Another way would be t