These two checks get confused constantly, mostly because both live under the umbrella of "checking my train" — but they answer completely different questions.
PNR status answers: "What's my seat?"
Your PNR status is tied to your specific ticket. It tells you whether you're confirmed, RAC, or waitlisted, and once allocated, your exact coach and berth or seat number. This is what you check to know where to sit.
Train running status answers: "Where's my train?"
Live running status is tied to the train itself, not your ticket. It tells you the train's current location, how delayed it is, and expected arrival at upcoming stations. This is what you check to know when to be at the station.
Why you often need both, at different times
Right after booking, PNR status is what matters — you want to know if you're confirmed and what to expect. On the day of travel, running status takes over — you want to know if the train's on time so you know when to actually leave. Confusing the two means checking the wrong thing at the wrong moment, like refreshing your PNR status hoping it'll tell you if the train's delayed (it won't).
Where CoSeat fits in
CoSeat separates the two cleanly: check your PNR status for your seat and booking details, or check live train status for the train's real-time location and delay — both with no login and no app required.