The difference is the price, no?
If I get paid 100 for playing a concert on one day, but 120 another day, did I get more productive? Either way I produced the same number of concerts, but got 20% more payment.
Measured in concerts my productivity was the same. Measured in other goods it went up.
From an economist perspective there is no difference between the two. Money is just a convenient metric to be able to compare the value of multiple goods.
You don't think of you salary as the power to buy X burgers or Y beers but really it is what it is. It is just easier to say I earn XXXX$.