* It's a dynamic information source, not a yearly printed paper catalogue or a reference printed every 5 years or so, this can change with updates.
* The Rarity Price Link is linked to rarity based on known surviving coins, whereas the paper format has no known methodology, and does not seem to be linked to other publications.
* You have a source of detailed photographs for every variety, so one can verify an exact coin.
* Rarity is defined as a number from 1 to 100,000. Those numbers for the first time may be added together to define a group rarity, or even a denomination rarity, so flexibility can be extended past individual coins.
* Paper publications are paper based, expensive and heavy to carry around, this is electronic and in the palm of your hand for easy / instant reference.
* Coin images may be enlarged to see the finest detail, whereas with paper sources there is neither colour or magnification.
* Going forward this approach can be expanded to other periods in history, to extend rarity comparisons and for this reason it is Copyrighted..