What distinguishes a portrait is that it is a representation of a single subject. Personally I would add a corollary that there is generally an expectation of s

What distinguishes a portrait is that it is a representation of a single subject. Personally I would add a corollary that there is generally an expectation of some artistic merit or high fidelity, so I think there's a subjective element to the appropriateness of the term. The OED has: 1.1 A representation or impression of someone or something in language or on film or television. ‘the writer builds up a fascinating portrait of a community’