What, if any difference, is there between the American Silver Eagle bullion coin and an uncirculated coin?
West Point mintmark, price, and availability. Silver bullion Eagles have been minted since 1986 and carry no mintmark. They have been minted at various locations and are currently minted at West Point sans mintmark. The uncirculated(burnished finish) Eagle is a collectors version of the Silver Eagle that was minted 2006-08, it had a price point between that of the proof and bullion versions. It has not been minted since 2008 due to planchet shortages. The Mint may very well have killed this program but so far, refuses to acknowledge it.
Since the beginning of the Eagle program, bullion versions have only been available through the Mint's Authorized Purchaser network who then make the coins available through the dealer chain. There are only a few APs because they have to enter into multi-million dollar contracts with the Mint to purchase Eagles. The bullion version typically tracks silver spot price plus a couple dollars with a few exceptions(1996 is the key date with 1986 and a couple others commanding modest premiums due to lower than average mintage). The bullion program has been going nuts the past couple years with almost 30 million minted last year and over 32 million this year. The uncirculated Eagles were available for purchase directly from the Mint.