cerificate vs masters

What is the difference between being a CNM with a certificate and a CNM with a masters? Is it like the same thing but the one with the masters took a few extra courses to make enough units/credits to count as a masters? Or is it for a nurse that already has a MSN say as a FNP and wants to also be a CNM??

Yes and yes.

Certificate programs were more common before the MS(N) became the preferred or required degree for CNMs and other APNs. Some states mandate that CNMs and/or ANPs have a graduate degree, others are moving in that direction. The certificate programs are dying out in favor of MS/DNP programs, since ACNM will require people to have a masters (or higher) degree for entry to practice in 2010.

Post-master certificate programs are for people with graduate degrees in other areas. For example, my class had 2 PMC students. One was a WHNP, the other was a FNP. Both wanted to add intrapartum care to their scope of practice. There's no reason why they should have to take the masters core classes - like theory or research - over again. They also had to do fewer clinical hours in antepartum and gyn care, since both of those had been covered in their NP programs. The curriculum for a PMC is pretty tailored to what the student has done in previous degrees.