Mantou ?? - plain steamed bun

What is the difference between Chinese bao/baozi ?/?? and mantou ???
Boazi is bun with filling and mantou is without filling. The word bao ? in boazi means 'wrap' so it is obvious with filling.

Mantou ?? is the staple carb for Northern Chinese more than rice, it is eaten at breakfast, lunch and dinner in place of rice. Plain mantou's texture is normally a bit chewy not like Cantonese cha siu