Tickets? That would be the conductor. (I'll edit my post above.)

The Cardinal is a single-level long-distance run that doesn't have a dedicated trans-dorm car, so there's no dedicated place for the conductor to work except for in the cafe, which is why you saw him there.

And no, they're not the same person...or I wouldn't have listed them as separate job descriptions above! Conductors are operating crew members and, like flight attendants and pilots, are governed by the federal Hours of Service Act, which is why they usually work shorter shifts (around eight hours--they cap out at 12) and therefore return back to their home base at least every other night, if not every night (i.e. on NEC Regional or Acela runs, they'll usually work BOS-NYP (4 hours) and then NYP-BOS (4 hours), for an eight-ish hour workday). OBS staff (including train attendants) are not governed by this, and so they usually stay on the train until its endpoint and often work upwards of 20 hours per day for the time they're on board.