Difference in location between tracking softwares?

Why is Flightaware showing CZ399 way above Russia in the Laptev Sea headed toward the north pole and flight Radar24 is showing it just south of Bilibino Russia? Flight Aware shows the flight plan over russia and over northern Alaska. FlightRadar24 shows the flight plan over the water above Alaska, down thru Canada over the Hudson Bay. Why the discrepancy? I track flights a lot but I still dont’ know everything about it. I use both trackers, each has their own best qualities and FlightAware is ALWAYS first to show departure and flight details before departure. FlightRadar gives more details while in flight. (IMHO).

Thanks for any info.

Here is a link to the flight. flightaware.com/live/flight/CSN399

When a flight isn’t in an area where we’re receiving position reports (radar, ADS-B, datalink, etc) we’ll continue to estimate the position of the flight from the best available information and clearly mark those positions as estimate and turn the plane grey instead of the usual green. I’m not sure what other sites do, they may show it in the last place they were able to locate it and hours later jump it to a new location.

From what the flight has flown over the last few hours since your post, our estimated path over northern Alaska was also correct.