A homogeneous mixture is a uniform mixture consisting of only one phase, such as liquid, or solid in the case of an alloy. Also, for a homogeneous mixture, any reasonable amount of the mixture has the same composition and properties as the whole. Thus tap water is a homogeneous mixture. Heterogeneous mixtures are mixtures with an inconsistent, non-uniform composition. The constituent parts of a heterogeneous mixture can be mechanically separated from each other. Thus, orange juice is a heterogeneous mixture because you can use a filter to strain out the pulp and have a substance with different density, consistency, etc.