Modern coin silver is 830 parts silver and 70 parts copper(used mainly in forks, spoons, etc.), "old" coin silver can be 825 parts silver.
Sterling silver USA is 925 parts silver, european is 930 parts silver.
Pure silver = fine silver = chemical pure silver = at least 999.9 parts silver.
The higher the content of silver, the lighter color and the more resistant the alloy is to tarnishing. Coin silver has a grayish color, compared to sterling. Coin silver is less malleable and work hardens alot faster than sterling silver. It's main virtue is that is a bit cheaper than sterling.
Fine silver hardly tarnishes, but its to soft to use for most applications. I use it mainly as silver wire when doing filigree work.
Best regards
Rolfkt