Hello.
If you want to  use your caste certificate for having reservation in any  vacancy or in any type of application then you can use your state caste certificate when the application comes under the state that means the vacancy is of your state and you are going through the reservation and if the opportunity given to you is from the central government then you definitely will have to use Central government caste certificate.
For example if you are going for the railway requirement then this opportunity  is given to you by the central government then you will have to use Central government caste certificate, state government caste certificate will not work here.
Best of luck.