I have seen these two words - private and permissioned, a lot. Sometimes, they're used interchangeably. I don't believe these words have the same meaning. Can anyone give a detailed description differentiating these two types of blockchains?
They are definitely not used interchangeably since they have a very different meaning/purpose:
Private blockchains are private because of the genesis block they are using. Their blocks do not match with any other blockchains (you cannot link blocks from the main net to blocks of a private net with a different genesis blocks as the block header hashes won't match).
Note that any node can connect to a private blockchain if it knows a bootstrap node address to sync, the network id, and the genesis file. This node can perform any action on the private net; mine, make transactions, deploy contracts, etc.
Permissioned blockchains on the other hand offer an access control mechanism so that peers are allowed or rejected based on a control value (an address, a certificate, etc.).
Is a blockchain, where we allow only known nodes to participate in the network. Ideally, it is internal for an organisation, a bank per se.
The first primary difference between a properly conceived permissioned blockchain network and an unpermissioned blockchain network is whether the participants in the network have an ability to restrict who can participate in the consensus mechanism of the blockchain’s network.
Is a blockchain where we can allow certain actions to be performed only by certain addresses (wallets)