I'm on KBin.
Active is either brand new threads like this one (at the time of posting this comment) or older threads with lots of actual activity in terms of comments and upvotes.
Hot is generally more consistent in showing threads from within the last 24 hours, including threads with smaller amounts of activity.
I tried this without the power tool and it didn't work very well. I have a much newer car now, but I'll keep this in mind for the next time I need to clear up old headlights.