What's the difference between a live wallpaper and a still wallpaper?

A still wallpaper is a static image — the same pixels every time you wake your phone. A live wallpaper animates, usually as a short 3–6 second loop with subtle motion (parallax drift, foreground breathing, lighting shimmer).

On iPhone, live wallpapers play on long-press of the lock screen (the same way Live Photos in your camera roll play). On Android, they play continuously on the lock screen as a video.

Live wallpapers don't use significantly more battery — they only play when the screen is on, and modern phones decode short loops very efficiently. Don't worry about it.