The Glockenspiel is an instrument that often gets mistaken for a xylophone!
And there are two main reasons for that. First off, they are very similar instruments.
The only real difference between a glockenspiel and xylophone is that xylophone bars are made out of wood, while glockenspiel bars are made out of metal. This also makes them sound rather differently, as metal bars tend to vibrate and resonate a lot better than wooden ones, but at first glance, they are the same instrument to the untrained eye.
The second, much larger reason for people mixing them up is rather inexplicable. Manufacturers have been for years making glockenspiels and marketed and sold them under the name xylophone, especially for kids. This made quite a confusion in the general public, as people for decades learned that an instrument is called a xylophone, whether it had metal or wooden bars.