The structural difference
CBSE examinations are entered through affiliated schools. NIOS allows registration as an independent learner. For a family that does not want a school timetable, that difference usually decides the question.
Where each one fits
Neither board is 'better'. They fit different family situations.
- NIOS: flexible pacing, independent registration, multiple examination opportunities
- CBSE: dense alignment with Indian entrance syllabi, familiar to institutions, requires school registration
Do not skip the eligibility check
Whichever board you choose, confirm the current eligibility criteria published by the examination or institution your child is aiming at. Criteria change, and a certificate is not the same as automatic eligibility.