Wikipedia lists 饺子 as the simplified Chinese characters for jiaozi.
The word refers to a Chinese dumpling made from a thin wheat-flour wrapper folded around a filling, often minced meat, vegetables or both. The traditional-character form is 餃子, while mainland China’s simplified writing system uses 饺子. The pronunciation is jiǎozi in Hanyu Pinyin.
Jiaozi can be boiled, steamed, pan-fried or deep-fried. Their shape is often associated with the gold and silver ingots used in imperial China, which helps explain their strong connection with prosperity and good fortune. They are especially prominent during Chinese New Year, particularly in northern China, although they are eaten throughout the year.
The listed alternatives are different foods. 烧卖 refers to shaomai, an open-topped dumpling; 馄饨 is wonton; and 包子 is baozi, a filled steamed bun with a different type of dough. Similar appearance does not make these names interchangeable: their wrappers, shapes, cooking methods and regional traditions differ.