Like cars, the basic principles of most sewing machines are the same.
At the heart of the car is the internal combustion engine, and the core of the sewing machine is the coil stitching system. The coil stitching method is very different from ordinary manual sewing. In the simplest manual stitching, the sewing person wears a thread in the small eye at the end of the needle, then passes the needle line completely through two pieces of fabric, from one side to the other, and then back to the original side.
In this way, the Needles drive the line in and out of the fabric, stitching them together. Although this is very simple for handwork, it is extremely difficult to pull with a machine. The machine needs to release the needle on one side of the fabric and then grab it again instantly on the other side. It then needs to pull all the loose lines out of the fabric, turn the direction of the needle, and repeat all the steps in the opposite direction. This process is too complex and impractical for a simple machine, and is only useful when used in a shorter line, even for manual purposes.