Why is wine a solvent but sugar is not?
Uh ... because sugar is a solid ?
Wine is a solution of water and ethanol plus some other chemical compounds. In this case they are toally miscible, meaning that they can mix in all proportion.
Sugar can dissolve in water, and here we can describe how much by the term solubility.
Sugar would be the solute and water the solvent.
Technically, a solution contains a solvent ( gas, liquid or solid ) and a solute ( gas, liquid or solid of different chemical ).
Separate names with a comma.