Quality issue?

Your first has an exposure problem as shown by the histogram:

A histogram like this indicates a flat contrast arm picture. Blacks and whites are missing. This is normally done by a digital filter, and gives a specific look, but that is less interesting for stock, as the buyer can create such a look on his own, but it's very difficult to recover the missing information. The white balance is wrong, too cool.

Your second is slightly underexposed. All in all, it is not one of the best firework pictures.