The main difference between a flat chisel and a chisel lies in their blade thickness and usage. A flat chisel is a type of chisel with a thinner and wider blade, with a longer wooden handle and no iron hoop. Flat chisels are mainly used for trimming and carving operations. Due to their thin blade, they are prone to bending and are not suitable for use as a chisel. The thin-walled characteristic of flat chisels makes them more flexible when dealing with wood surfaces. They can be used in conjunction with a hammer for tasks like chiseling holes, digging, and grooving.

A chisel, on the other hand, is a tool with a thicker and narrower blade, usually with an iron hoop on the wooden handle. Chisels are specifically designed for mortising and are essential tools in woodworking for joining wooden components. Chisels come in various shapes and angles, including flat chisels, round chisels, and slant chisels, mainly used for tasks like chiseling holes, digging holes, and grooving.

In summary, although flat chisels and chisels may look similar in appearance, they have different functions and usage scenarios. Flat chisels, with their thinner blades, are mainly used for trimming and carving wood, while chisels, with their thicker blades, are specialized for precise woodworking operations like mortising.