Silver Proof Sets started again in 1992, and the used coins (dimes, quarters, & half dollars) were made with 90% silver. The last couple of years the silver was upped to .999% silver.
I believe shug23 is asking if the 'penny' in the regular proof set (let's say 2020) is exactly the same as the 'penny' from the 2020 Silver Proof Set. Any differences?
I personally do not know. I WISH there IS a difference, because I've already gotten the base proof set this year, and would prefer not to have to pay $105 for the silver set and only get four coins that are different than what I already have (ie; I would get three repeats). At least in the Canadian Silver Proof Sets, ALL COINS (even the cent) are made of silver.