The frame is identical to the 2012 yz250f according to Yamaha.
Not quite "exactly" the same. The rear triangle is different for the WR to make room for the air filter and battery. If you look at the one of the sides of the frame, left I think, you will see where the mounting point is for the YZ250F, the tapped hole. Whereas the WR has a tab welded to the frame.