My cousin have qualified both exams and without a doubt, CDS is the toughest one. The reason being that the CDS paper is created by the UPSC, whereas AFCAT is prepared by the Indian Air Force. So you have to think a lot when attempting CDS questions, it tests your conceptual knowledge. AFCAT touches on basic topics and is much easier.
The following points must help you in a better understanding:
Here's a table reflecting the previous three-year cut-offs for AFCAT and CDS exams-
Exams |
2019 cut off |
2018 cut off |
2017 cut off |
AFCAT |
133-140 |
160-140 |
150-155 |
CDS |
95-128 |
NA |
120-260 |
Do not pre-suppose that clearing AFCAT with SSB will clear your path to the Indian Air Force, because apparently the final cut off is quite high, so if your AFCAT score is really high, between 140-180, only then will you be able get into the permanent commission.
However, if you clear the written and SSB in case of CDS, then you'll definitely join any of the forces and get into PC.
Study thoughtfully and try to prepare with determination and an open mind.