Here's a position from Moskwa v. Kogen that illustrates the differences between rook endings and queen endings discussed in the last post.
Robert's pawn is nearer to queening but that's not nearly as big an advantage in a rook ending because the Black rook will sacrifice itself for the new queen after which the White rook won't be able to handle the Black king and connected pawns alone and may be forced to sacrifice itself in return. A queen could handle the Black king and pawns with ease.
The game went 39.Rc8 Rd3 40.Ke6 b3 41.d7 a4 42.d8=Q+ Rxd8 43.Rxd8 Kc5 and in order to draw White will have to hustle his king over to help with the defense and sacrifice his rook at the right moment. On the other hand, 39.e5! would have won after 39....Rd3 40.e6 Rd5+ 41.Ke4 Rxd6 42.e7 42.Rxe7 42.Rxe7 because the White king is close enough to assist the rook before the Black pawns advance too far.
Cross posted at Prospect Chess