What's the difference between "Plants," "Mushrooms," "Pests," and "Health" mode?
Plants — identifies houseplants, trees, and garden plants.
Mushrooms — identifies fungi (see the safety note above).
Pests — identifies insects and garden pests.
Health (Diagnose) — looks at a plant you already have and tries to identify what's wrong with it (pests, disease, nutrient issues, etc.), rather than identifying the species itself.