There’s a bit of terminology creep when discussing Kerberos tickets. Mimikatz and Rubeus are actually dumping Kerberos data structures (as .kirbi files), which contain both a ticket and the corresponding session key. People tend to call these .kirbi files “tickets”, but it’s worth keeping in mind that they contain both pieces of data (as a “ticket” in the Kerberos sense, not the hacker’s sense, isn’t useful without the corresponding session key).