Yes, they're not the same thing. First, the credentials were leaked. Then, the service was hacked using the leaked credentials. Afterwards, information obtained in the hack was leaked.
> Hacking is the act of identifying and then exploiting weaknesses in a computer system or network, usually to gain unauthorized access to personal or organizational data.
In this case, they weren't exploiting any weakness of the system thus they did not hack. Logging in is an authorized action. Who is using those credentials is another story. Clearly it is a user mistake. It's like leaking your SSN and saying people hacked your credit card.
Social engineering is social engineering. You're hacking humans if anything, but you're not hacking a system by definition. You can social engineer people for other reasons than hacking a system.
