上圖是Bullion Coin 或 Uncirculated Coin, 而下圖是 Proof Coin
"What is an un-circulated coin?"
Uncirculated means a coin has not had any wear, such as the wear a coin might experience when it is used in commerce. Handling a coin, as well as improperly storing a coin, can result in wear on the surface of the coin. This wear, even if very minor, will cause a coin to no longer grade uncirculated.
(Uncirculated Coin 不可有花痕, 而有花痕的新幣可以俾降級不可叫 Uncirculated)
What's a proof coin?
A newly minted proof coin is also Un-circulated, however it is the way it is made that causes a difference in appearance and qualifies it as a "proof". To understand this, let's look at how coins are made. Coins are produced when two dies strike a blank piece of metal with tremendous force. One die is engraved with the front (obverse) design for the coin. The other die has the back (reverse) coin design on it.
(Proof Coin 因為是用特別支術製造, 所以表面會滑如鏡, 而價格也會貴過 Bullion Coin. 因為Proof Coin 價格貴, 所以多數有禮盒和証書跟隨)