NCBTMB = National Certification Board for Therapeutic Massage and Bodywork = the organization behind the exams
NCETMB = National Certification Exam for Therapeutic Massage and Bodywork
NCETM = National Certification Exam for Therapeutic Massage
For more info, please check the NCBTMB Applicants FAQ:
http://www.ncbtmb.com/applicants_faq.php#1i