Hi,
From my experiance, in Govt services there is no differene between CWA & CA, but in Pvt sector CA is definitely having an edge. This fact can be verified that in most of the Govt job CWA are working as an employee, as the opportunities and salary are higher for CA in Pvt sector most of them would opt for Pvt sector job only. Even in some Pvt sector companies accountant means only CA and not the CWA, you can blame the pscyhe of these Companies.
There is very little scope for CWA in practice as the fees are less and Cost Audit report consist audit certificate which very parameters are very strict for an any auditor. A small amount of negligance and COP is gone.
You may not find much of CWA in Practice.
Hence my suggestion is opt for CA it might tough but in longrun you get the benefit.
I am qualified CA & CWA and previously worked with Central PSU and from last four years I am working in Pvt sector. I can tell you that doing both course would be tough but this combination is deadly combination in the job market.
Regards
Narinder Singh