Both are equivalent, as in near equal but not the same or interchangeable. For private practice and further studies, they are the same. For a vocation in academics, they are not. DNB candidates require atleast 1 extra year of working as an Senior Resident to get the job of an Asst. Professor.Its a general perception that people who do end up doing DNB are the ones who couldn't secure a MD seat because MD exam is more difficult than DNB.

but its all upto the person how he/she takes it academically.