Not much. Although recently, offside rules about crossing the red line in the neutral zone have changed. Offside is only called for violations over the blue lines on either side of the neutral zone. Equipment has obviously changed as well. It was not mandatory to wear helmets in the NHL until the 1979-80 season for players entering the league. Veteran players could continue to go bareheaded. 1973 marked the last appearance of an goalie without a mask in an NHL game. Sticks were originally completely straight, making it harder to pass and shoot, but in about the 1960's the blades took on a curved shape. Pads were also made of entirely natural materials in the past, but now they're all made of lighter, more breathable synthetic materials. The players are coming more from Europe than from bef