Are all homogeneous mixtures just solutions?
Homogeneous and heterogeneous classifications are scale-dependent. What we mean when we say a mixture is homogeneous is that there are no visible phase differences on the scale of interest.

For example, milk (when homogenized) and lotions are both examples of colloidal suspensions. There are no phase differences at the human scale, but neither one is a solution. On a more microscopic scale, you could call the suspended micelles phase boundaries, and in that case might not call the mixture homogeneous.

"Solution" always implies mixing on the molecular level (single-phase). 

To summarize:


  Solutions are always homogeneous mixtures, but homogeneous mixtures are not always solutions.