Quote:
what constitues "all different" stamps in large WW collections
I never ear that for a WW collection, all different is a term use by seller for their 1000, 2000, 10 000 packs of stamps.
For me it's simple, at the base someone design a stamp, the rest; paper varieties, color shades, error, are production related. I collect stamp for their different design. No one as no one as completed a WW collection of all the stamps issues in the world, adding all the production related difference will make it even less possible.