The sodium light source is extremely efficient in terms of lumen's per watt and also lamp life. The light it gives off is slightly warm and yellow in colour.
Similar idea to Sodium, but offers many more colour options which makes it great for showrooms and lighting effects.
Starting to become somewhat overshadowed by the more versatile LED option these days, but still showing good energy savings against some of the lower output traditional flood lighting.
Die-cast is more rugged but polycarbonate can be an ideal solution to corrosion issues particularly in coastal areas. if you're installing up a height in difficult to access positions, look out for floodlights with easy opening clip fixings that make it easier to change lamps and gear in the future.