CA

Course wise difference is already known to all.
Basically, a chartered accountant is someone who has expertise in Taxation, accounts and auditing. On the other hand, a company secretary is one having expertise in all the laws, rules and regulations.
Both have different work fields and opportunities.
We can conclude by saying that
CA is for the masses.
CS is for the classes.
As anybody and everybody can approach a chartered accountant for basic accounting or Taxation work but same is not the case with company secretary.

If you want to do CA, then I will suggest you to go for B.Com as it is related and you will find the similar subjects also. BBA is related to business administration. You will read about accounts, tax, finance, etc. in B.Com as well as in CA also.

If you can complete both of them without compromising on grades in any of them you will definitely benefit more than others who would have pursued just one. You have an advantage of having two qualifications once completed. Strong Future scope if performance is good.

You can complete CA after BBA but will require hardwork and dedication. You may evaluate taking external help to clear CA.

BBA syllabus may not directly benifit you in clearing CA. To clear and complete CA is quite tough. It is a good idea to take external support to clear CS.

You are advised to do B.Com or BBA by regular or distance learning as per your choice.