the difference between normal and gold is that gold is a single dip tan which means the colour you are sprayed darkens slightly whereas normal is a double tip tan(which most tans are) where the colour you are sprayed is a guide colour for us and washes off leaving the tan colour underneath. Also gold is a golden brown where normal is more a brown.
I personally prefer 10 gold, its more natural, fades off nicely, doesnt come off on clothes or bedding but think you should stock bothe single and double dip and explain the difference to clients. I do and most go for gold.