1970 s Jefferson nickel mint mark

Was there 2 separate mint marks for 1970-s? I have sound a fat and a skinny s mint mark. Which is correct?

 

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I'm not sure, but I think one could be for the proof, and one could be for the business strike.

 

(In 1970 the SF mint issued regular "S" nickels and proof "S" nickels.)

 

All these came as in the picture. Did they put proof coins in these wrappers? None of them look like proofs they all appear to be weak business strikes. Out of 40 nickels I only found 2 with the skinny S so did they hit the business strike with the proof S?

 

It could be that because the mint marks were hand punched into the dies, and one was punched deeper than the other.

 

Question. How do you tell the difference between the 1970 s proof and the 1970 s business strike in circulated coinage? Would it still show noticeably shinier fields? Is there any other way to tell the difference besides luster?