cmi5 bridges the gap between SCORM and xAPI. xAPI on its own defines how to record learning experiences but not how an LMS should launch and manage a course; cmi5 adds those missing rules — launch, authorization, and a defined set of reporting verbs — so xAPI content works cleanly inside an LMS the way SCORM does.
In short: use SCORM for maximum LMS compatibility with self-contained courses, xAPI to track richer or non-LMS learning, and cmi5 when you want both — LMS-managed launch plus xAPI’s flexibility. See SCORM vs xAPI.