"Amount" vs. "quantity" in generic?

It seems like both are used when referring to generic nouns:

Product:
    name price amount total
    ---- ----- ------ -----

or,

Product:
    name price quantity total
    ---- ----- -------- -----

So which one should I use?

I've also seen someone use amount instead of total in case of shares:

Shares:
    share price quantity   amount 
    ----- ----- -------- ---------
            *      *     price*qty

Should this be correct or not?

Solution 1:

English divides nouns into countable and uncountable. Uncontable nouns are those like sand and rain, where you can't say three sands or three rains but have to say three grains of sand or three drops of rain.

You can only use amount for uncountable nouns. You can only use number for countable nouns. You can use quantity for either.

I have a large amount of sand.
I have a large quantity of sand.

I have a large number of chairs.
I have a large quantity of chairs.

So if your products can be both uncountable and countable nouns, you should use quantity. However, quantity sounds wrong if you're talking about money.

I see no advantage to using amount rather than total for the total cost. You can get away with it when you're talking about shares, since shares are countable, so amount cannot refer to shares. However, if you also have uncountable nouns possible for your products, then people could get the amount column and the quantity column confused. So I'd recommend using your second example.

Solution 2:

Let's see the definitions (NOAD):

• Quantity: the amount or number of a material or immaterial thing not usually estimated by spatial measurement: EX: the quantity and quality of the fruit can be controlled.
EX: note down the sizes, colors, and quantities that you require.

• Amount: a quantity of something, typically the total of a thing or things in number, size, value, or extent.

But for amount the second meaning given is "a sum of money", EX: They have spent a colossal amount rebuilding the stadium.

Amount can also be a verb, unlike quantity, and it's the following:

Verb [intrans.] (amount to) come to be (the total) when added together : losses amounted to over 10 million dollars. [And others side meanings not related with "quantity acception".]

I'd like to note that the two are given as synonyms by the Oxford American Writer's Thesaurus, but it's pretty much obvious that they're not absolute synonyms and therefore are interchangeable in some contexts only.

So considering all of this, if you mean the total of products, I'd use quantity, if instead you mean the total of money, I'd use amount.