1, material: thermal underwear material is better, such as wool, cotton, polyester fiber, etc. , which can provide better thermal insulation performance, while the thermal vest is made of light and thin materials, which has relatively poor thermal insulation performance.

2. Design: The thermal underwear is designed to be closer to the skin, reducing air flow, thus providing a better thermal effect, while the thermal vest is very loose and can't be close to the body, so the thermal effect is relatively poor.