What's the difference between Uniqlo thermal underwear 1.25 and 2.25?

1.25 is just an ordinary thermal underwear. If it is 2.25 times that of thermal underwear, it will be thickened and super warm. You don't need heating in the north. Wear such thick thermal underwear. If the south of Guangdong is wet and cold, you can wear a coat outside when you go out.