photoreceptor cell differentiation
http://purl.obolibrary.org/obo/GO_0046530
The specialization of organization of a photoreceptor, a cell that responds to incident electromagnetic radiation, particularly visible light. An example of this process is found in Drosophila melanogaster. [ GOC:ai http://openisbn.com/search.php?q=0198506732&isbn=1/ ]