Difference between convergent and divergent evolution

When two different species with the same ancestral origins have different traits, it is divergent evolution. Darwin's finches are an example of divergent evolution. There are about 15 different species of Darwin's finches derived from a single species, but they differ in beaks because they adapted to different diet.
When two different species with different ancestral origins have similar traits, it is convergent evolution. Let's take for example fish and dolphins. Dolphins are mammals and not fish, but they have fins just like fish. Although fish and dolphins have different ancestral origins, they develop similar structures because they live in similar environmental conditions.