'Sprite' is a term for game development, not just game art. It refers to any 2D object brought into the game as an object, rather than as a background or larger piece of artwork. Technically, a sprite doesn't even need to be made from pixel art, it can be brushed together in Photoshop or even made from a photo. Of course, technically, 'pixel art' doesn't necessarily mean something is drawn dot by dot, since any 2D image that can be displayed online is pixel art.
*shrugs*
Typically, the term 'sprite' is used for characters of objects in a 2D pixel game.