Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms. For example H20 is a compound, it has fixed ratio of hydrogen and oxygen. If the ratio changes it is no longer water. So, we can say --Compounds have a fixed composition.
Homogeneous mixtures are mixtures that have the same proportions throughout a given sample or multiple samples of different proportion to create a consistent mixture. For example, blood is a homogeneous solution or a solution of sugar in water where sugar is completely dissolved in water makes a homogeneous solution. So, if we take any sample from blood or a sugar-water mixture, we will get same composition of its chemical individuals. In sugar solution we will get same ratio of water and sugar no matter which sample from the solution we check on.