Two coins graded by PCGS. One is MS and the other is SP. Satin Finished coins were only issued in mint sets were they not?
At first both PCGS and NGC used the "MS" designation on coins like this and just noted satin finish on the label. Later they decided to separate these out and call them "SP" like on the second picture. So there is no difference in the coins-it is just a matter of the grading companies changing the way they label the coins. Here is a brief description from NGC: "SP is a catchall that is applied to a variety of finishes that are distinct from the appearance of circulation issues but do not fit any of the Proof categories. Specimen can describe early US coins with bold strikes, very brilliant fields and semi-frosted devices as well as modern US coins that were produced with matte or other unusual finishes." https://www.ngccoin.com/news/article/7708/learn-grading-sp-and-pl-prefixes/ And another article talking about Silver Eagles going from "MS" to "SP" https://coinweek.com/education/coin...-you-need-to-know-about-w-mint-silver-eagles/
And apparently they did those slabs both ways: NGC called them all "SMS". I think early on they called them "MS" with them labeled Satin finish on the slab, and around 2006, changed it to "SP" to differentiate it further. probably an internal disagreement started in 2005 over calling the satin mint set coins MS that resolved to being called SP in 2006. My personal opinion, I think they were trying to identify it with the TM'ed Satin finish logo slabs originally and it didn't work out so well for the population census organization, so they changed it otherwise they all would be of the design and date and it's not the same finish.
