gecko -
any of various small chiefly tropical and usually nocturnal insectivorous terrestrial lizards typically with immovable eyelids; completely harmless
lizard relatively long-bodied reptile with usually two pairs of legs and a tapering tail
gecko -
Any lizard of the family Gekkonidae. They are small, carnivorous, mostly nocturnal animals with large eyes and adhesive toes enabling them to climb on vertical surfaces.
Wikipedia
Geckos are small to average sized lizards belonging to the family Gekkonidae, found in warm climates throughout the world. Geckos are unique among lizards in their vocalizations, making chirping sounds in social interactions with other geckos. An estimated 2,000 different species of geckos exist worldwide, with many likely yet to be discovered.