The disclosure discloses a lamp and a lamp assembly. The lamp has a splicing structure and a connecting side, the splicing structure is arranged on the connecting side, the splicing structure includes a first clamping groove and a second clamping groove extending in a same direction, and a notch of the first clamping groove and a notch of the second clamping groove face in opposite directions. Two lamps can be spliced through a lamp connecting module to form a lamp assembly. The lamp connecting module includes a first lamp connector and a second lamp connector, each first lamp connector can be clamped with two first clamping grooves of the two lamps at the same time, each second lamp connector can be clamped with two second clamping grooves of the two lamps at the same time, and the first lamp connector is detachably fixed with the second lamp connector.