Taillight and Tail lamp

Taillight noun - Lamp (usually red) mounted at the rear of a motor vehicle.

Tail lamp is a synonym for taillight. In some cases you can use "Tail lamp" instead a noun "Taillight".

Tail lamp noun - Lamp (usually red) mounted at the rear of a motor vehicle.

Taillight is a synonym for tail lamp. You can use "Taillight" instead a noun phrase "Tail lamp".