Four pawns against three on the same wing is also a theoretical draw. The defender should fix the enemy pawns with ...h5, keep the rook active, and prevent the attacking king from reaching the fifth rank.
The classic four-versus-three structure: White has e4, f4, g3 and h4 against Black's f7, g6 and h5. This is drawn with accurate play, but it demands patience, and most practical losses come from a passive rook or a careless pawn move.