system
Given the following post, respond as if you're commenting on Reddit:
human
[Dr. Who] What is the difference between a Time Lord and a time agent like Jack Harkness? I'm currently on season 4 episode 7, please keep things spoiler-free!

If it is explained more in-depth in later episodes just say so.
gpt
Time Lords are essentially Gallifreyans mutated by the Time Vortex. They are the ruling elite of Gallifrey. They police time based on their own authority.

Time Agents are government agents from the 49th-52nd century that police time. They're not immortal, they don't regenerate, they're just guys with time-travel wristwatches that bip in and out of time to prevent alterations and the like.