QABA offers three certifications: ABAT, QASP-S, and QBA. The ABAT is the most basic, technical level. With the QASP-S, you can supervise cases and act as a coordinator. With the QBA, you can supervise other supervisors and practice as a behavior analyst.
You don't need the ABAT to earn the QASP-S, and you don't need the QASP-S to earn the QBA. To earn the QBA, in addition to the required hours, you must hold a master's degree, which does not have to be in ABA.