The Singer 66 is an early model of sewing machine produced by the Singer Manufacturing Company. The 201 is a later model that was introduced in the mid-1920s. Both machines are treadle-operated, meaning they are powered by a foot pedal, and both can be used for various types of stitching.
The 66 was one of Singer's first mass-produced models and was very popular when it was first released. It is a simple machine that is easy to use and maintain, which makes it a good choice for beginner sewers. The 201 is more complex than the 66 and has more features, such as different stitch patterns and a built-in needle threader. It is also slightly larger and heavier than the 66.