Number of Threads
An ordinary sewing machine typically uses one or two threads to create stitches. In contrast, a serger—or overlock machine—uses three to five threads (or even more), which allows it to form strong, flexible, and more complex stitches, especially suited for finishing edges and handling stretch fabrics.

Stitch Type
A standard sewing machine usually produces lockstitch or zigzag stitches. These are sufficient for basic garment construction but not ideal for professional seam finishes. A serger, on the other hand, creates overlock or cover stitches, which wrap around the fabric edge and prevent fraying while allowing stretch and flexibility in the seams.

Edge Finishing
When it comes to edge finishing, a regular sewing machine requires manual techniques or the use of special stitches and presser feet to prevent fabric from fraying. A serger excels in this area by automatically trimming the fabric edge and enclosing it with thread in one seamless step, offering a clean and professional finish.

Cutting Fabric
Ordinary sewing machines do not cut fabric as they sew. Any trimming must be done separately with scissors. Sergers are equipped with a built-in blade that trims excess fabric while sewing, which saves time and ensures precision in seam allowances.