Dear student,

CBI is better than Police. CBI is a specialised agency, doing only crime investigation work, while the state police have to perform multifarious tasks. In any case, the organisation, unlike the state police, is not required to confront the public in many adversarial roles, requiring use of force.
For example, SP of CBI is more powerful than the state police SP . The truth cannot be farther from it. While the state police SP has a real authority to take decisions independently, the CBI SP doesn't. He is like a puppet who doesn't run the show unlike his counterpart in the state police.

Hope this information helped you.

Good Luck!!