Commodore had some success in the education market early on with its PET line of computers. While the later Commodore 64 was hugely successful, it did not enjoy as much success in the education market in part because of its design. It was felt that its smaller nature would make it easier to steal or damage. In response, Commodore created the Educator 64.
In many ways, Commodore was a very frugal company. The Educator 64 was created with, in many cases, leftover PET cases and refurbished Commodore 64 motherboards. Because of this, there are many slight variations of this model. However, in all of its variations, it was essentially a Commodore 64 in a much larger case.
There was one other major difference though. While the Commodore 64 would normally be connected to a color monitor or TV, the Educator 64 used a green monochrome monitor. I suppose this was done because it was cheaper but it caused problems with some software that expected a color display.
There was a lot of public domain educational software for the Commodore 64 so this wasn't a bad choice for educational purposes. However, by the time the Educator 64 came to market in 1983, the Apple II pretty much dominated the educational market. This makes Educator 64s relatively rare and certain individual variances much more rare.