Unfortunately, there are two quite different uses of the term "homogeneous" in differential equations.
1) As applied to first order equations, an equation of the form y/dx= f(x,y) is "homogeneous" if and only if f(ax, ay)= f(x, y) for any number a. That is the same as saying that f can be thought of as a function of y/x only.
2) As applied to a linear equation of order higher than 1, the equation a_n(x)d^n/x^n+ a_{n-1}(x)y/dx^{n-1}+ \cdot\cdot\cdot+ a_1(x)dy/dx+ a_0(x)y= f(x) is homogeneous if and only if f(x)= 0 for all x.