Answer
A quadratic function has a maximum/minimum.
A cubic function can have only a local maximum/minimum due to its end behavior.
Work Step by Step
The local maximum of a quadratic function is the same as the (global) maximum of the function because there is only one such a value of the function on its domain (it exists when the leading coefficient is negative). The same goes for the minimum (it exists when the leading coefficient is positive).
In the case of a cubic function, the ends of the graph go on opposite directions to $-\infty$ and $+\infty$, so there is no (global) maximum/minimum; any maximum/minimum can be only local.
