When is a State Action not a State Action: Dehradun v. Bajpai Confusion

Yaar samajh nahi aaya, please help. In Administrative Law, I'm stuck on Dehradun Municipal Corporation v. Bajpai (2016) and Rakesh v. State of Punjab (1976). Both cases deal with when a State Action can be considered a 'State Action' under Article 12 of the Constitution. But, yaar, I'm getting a mental block. In Dehradun, the Supreme Court held that the Municipal Corporation was a "public authority" under the Right to Information Act, but not a "State" under Article 12. Meanwhile, in Rakesh, it was held that the Punjab Roadways Bus was a "State" within the meaning of Article 12. But what's the criterion here? Is it ownership, control, or something else?