This tutorial of Khan Academy suggests that if dy/dx = f(x,y) can be written as dy/dx = F(y/x) then it's homogeneous differential equation.
Consider following example as dy/dx = x^2/y is separable but it also has been written in the form of y/x so is it separable and homogeneous both?
If you have $$ \frac {dy}{dx} = \frac{x}{(y/x)} $$ Then $\frac {dy}{dx}$ is a function of both $x$ and $y/x$. Since it not a function of only $y/x$, the differential equation you describe is not homogeneous.
As indicated by the comments, however, there are differential equations that are both separable and homogeneous.