来源 is similar to source and 发源 is more like the origin.
发源 must be related to the place where the object was originally created/appeared.
来源 just mean where something come from, whether it was the place that it originally created/appeared or not.
For example, the HIV 发源 from Africa, but the 来源 of the virus of a specific patient in Europe can a specific person that he have close contact with.