Scarcity
All the items in the game are limited by either time or quantity.
Time limited mean it may only be sold for say a few hours, a day, a week, a month, but after that it’ll be gone.
Quantity limited is exactly that, a limited amount is sold, say 1000, or 10000 and once all of those are sold out, they are gone.
Once these limits are up, they’ll be gone and the only way to purchase them after is from another player/seller on a secondary marketplace.
As a general rule of thumb, something that is more scare will be more rare, but that depends on how much demand there is for the item by the community.
Rarity
As all items will have a serial number minted onto it, if you are lucky enough to get the first one of a specific item, that may mean that generally it’s more rare (provided that item is popular) . Additionally, note that there are no ‘epic’ or ‘legendary’ or ‘common’ items types like traditional video games. Blankos Block Party items and rarity will be driven by the community and what is most popular and scarce. It’s all about demand and supply. There will be no loot boxes in the game, so what you buy is what you get.
When you buy your Blankos, it will come in a box like a physical toy. You can read more about boxed Blankos here. If you are a collector, it may pay to keep your Blankos boxed in mint condition as it may increase it’s value. Again this is dependent on how much demand there is for the item by the community and how rare the item itself is.