Direct answer
Use illustration instead of photography when the story needs abstraction, synthesis, privacy, metaphor, reconstruction or a non-literal visual argument. Use photography when the story depends on documentary evidence, identifiable place, real subjects or the authority of witnessed reality.
How to use it
- Choose photography when proof of the actual person, place or event matters.
- Choose illustration when the issue is systemic, conceptual or sensitive.
- Use illustration for future scenarios, hidden processes and emotional interiors.
- Use photography for accountability, documentation and direct evidence.
- Mix them only when the reader can tell which mode is doing which job.
Example
A profile of a musician may need photography. A story about how platforms shape creative labour may be better served by illustration because the subject is a system, not a single visible event.
Caveats and limits
Illustration can protect privacy, but it can also overgeneralise. The brief must define what the image is allowed to infer.