What is the relation between “Operation of type: payment”, “Payment” and “Effect of type: account_credited”?
Can “Payment operation” be submitted and not results in “Effect” (e.g. because of insufficient funds)?
A transaction is a group of one or more operations being sent to the Stellar network to all succeed or all fail together.
An operation is a command to the Stellar Network. This can be create account, send a payment, make an offer (to exchange asset for asset), change account settings, etc.
A payment is a transaction that includes a payment operation. The payment operation transfers the amount you want to send of the asset you want to send to the destination account.
All of the effects are API endpoints that let you see the history of operations applied to an account. The Effect of Type: Account Credited, is an endpoint where you can monitor incoming payments to an account.