Social networking sites (SNSs) and virtual communities (VCs) are popular online social media having similarities and differences. The paper investigated the difference in motivations and in the relationships from motivations to continuance intention between active users of SNSs and VCs. The results show that while connecting with old friends, meeting new people, seeking information, seeking entertainment, and seeking social support are significant motivations of both communities’ active users, active users of SNSs rate higher motivation to connect with old friends than VCs; seeking information and social support motivations have the same effect on the continuance intention of the both communities’ active users through attitude; connecting with old friends and meeting new people motivations have obvious different effects on continuance intention through attitude between the two communities’ active users.