Is Nanning Langdong Bus Station and Langdong Train Station very far from each other?

Do you refer to the Main Railway Station? If yes, these two are not located at the same place.
Langdong Bus Station ('琅东客运站'): No.186, Minzu Avenue, Qingxiu District
Main Railway Station ('南宁火车站'): No.82, Zhonghua Road, Xingning District
The distance between them is around 7.5 miles. You can take subway line 1 from Langdong Bus Station and get there directly.