noun
Refers specifically to the heir apparent to a throne, typically in a monarchy. Formal and official term.
王太子は来月、即位する予定だ。
The crown prince is scheduled to ascend the throne next month.
その国の王太子は、国民から広く敬愛されている。
The crown prince of that country is widely beloved by the people.
王子 is a general term for prince, not necessarily the heir. 王太子 explicitly denotes the heir apparent.
Compound of 王 (king) and 太子 (crown prince). The term is straightforward and follows standard Sino-Japanese word formation.