cmi5 is an xAPI Profile that bridges the SCORM and xAPI divide by specifying interoperability rules that inform how an LMS and xAPI activities communicate.
The Experience API or xAPI for short; is a specification document created by a consortium of learning experts led by the Advanced Distributed Learning Initiative (ADL), which is a US Government Programme. Whilst the document was being formed its prototype name was ‘project Tin Can’, but these days it is known by its official name, xAPI.