What's the difference between a mousse, a lotion, and tanning drops?

Mousses (like St. Tropez and Bondi Sands) typically develop in 1–8 hours and deliver the deepest, most buildable color in one application, usually with a tinted guide color so you can see where you've applied. Gradual lotions (like Bondi Sands PURE, Tanologist Daily Glow, Tan-Luxe The Gradual) build subtle color over multiple daily applications and feel more like moisturizer. Drops (like Coco & Eve) are concentrate you mix into your own moisturizer or serum, mostly used on the face for customizable intensity.