Personally i don't know if there are any specific design elements different but I doubt it.
If I assume catalogs have any slight validity then the price difference listed between the two tends one to the conclusion that the difference between the coins manufacture
is important to many collectors and not just me.
For me knowing that a coin was intended to be use in everyday life is much more attractive and desirable than a proof or special set coin.
Why? Darn if I know but that is the way I feel about it.
The 1964 coins I have had in this specific case had much more sharpness and clarity of fields.
Maybe looking at one coin in hand a person wouldn't notice the difference.
But the difference is obvious when in a page with all the other dates surrounding it.
Is there a difference between the proof and business strikes? I don't mean the technique of striking them but a difference in design. If not, why would you care if it came out of a proof set?