Is meningocele and spina bifida the same thing?

Yes: Meningomyelocele and spina bifida are an interrelated problem, in that all people with the former have the latter.

Related terms: Spina bifida is a fancy way to say that a spine segment or segments did not close along their backside. Meningocoel is a term for the spinal cord & elements that would balloon out the back if the spine did not close and contain them. People often use the term to describe a similar process. The most common location is at the base of the spine, but both could happen in the neck also.