How do independent variables differ from dependent variables?

The dependent variable is the physical quantity that changes with respect to the independent variable.

They are totally different..

Dependent variable: The physical quantity that change with respect (relative )to the independent variable

So here is an example,

Let ##y##=##2x^3##+##5x^2##-##7x##

here ##y## varies with respect to values of ##x##

values of ##x##===>Independent variable

following images state differences of Independent variable &dependent variable