Lightbulbs— old-school ones — use the glow from a metal filament to generate light (and heat) simultaneously. The filament resists the flow of electricity, causing the metal to heat up and glow. The vacuum inside the bulb prevents it from burning/melting. The light and warmth are products of the electricity flowing through the wire filament.
Phone screens are illuminated by LED — light emitting diode. They are a semiconductor circuit that makes light when electricity flows through it.
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