My fiance got diagnosed w/a herniated disc in his neck 3mnths ago &today the doc said he needs an MRI done. Will he need a neck or cervical spine one?

Same. 'neck' and cervical spine MRI 's are the same...Looking @ the cervical discs , spinal cord etc. Best of luck.
Cervical spine. It sounds like he will require a MRI of the cervical spine. Check out spine-health.Com. Good luck.