The distinction is who initiated it, and once you see it the whole thing is predictable.
Pull payments. You give somebody permission to take money — a card payment, a direct debit. The mechanism is designed around the idea that the taker might be wrong or dishonest, so there is a built-in route to reverse it. Card schemes call it a chargeback; direct debit schemes have their own guarantee. The reversal is part of the product.
Push payments. You instruct your bank to send money — a bank transfer, an instant payment. The system is built to settle finally and quickly. There is no reversal mechanism because the whole design assumes you meant it. Once it lands in the recipient's account it is legally theirs, and the bank has no button.
Your two friends used one of each. The card dispute went through a process that exists. The transfer had no process to go through, which is what "it is gone" means — it is a statement about the rails, not about effort.