Mostly marketing, the only thing it shares with the M70 is the trigger, the bolt and receiver are the same as Browning's AB3 made in Japan (FN owns both of them). Winchester claims it's made in Portugal, but that's only where they are assembled.
If you do a quick google you will see the same bolt and 80% same receiver, Winchester went with Savage style barrel nut on it instead of the recoil washer, and use a recoil lug in the stock sort of like Savage Axis. Basically a cheaper manufactured AB3 with less machining on the receiver.
Not a bad budget rifle, I have a pair of AB3's and they are pretty nice for a budget gun. I like the mags better on the AB3, and they have a decent trigger system too, lightweight for carrying around.