Yes there is a difference and that is why you should read the bottles. But the real question is . . . is there a PRACTICAL difference for YOUR application?
Some products prevent gelling to -40, other only to -25. If you live in a climate where the record cold temp is only -18 then is there any differnence for YOU? By the way, none actually remove the water, the water is typically emulsified and held in suspension and flushed through the system and burned along with the fuel. Some conditioners have cetane boosters, some do not. Some conditioners have cleaning properties, some do not.
I don't recommend any one brand, we use several, and have had good results with all of them. We use them in our truck fleet and can put 100,000 miles on the fleet in the winter months. I never criticize any one brand, but I don't advocate any one brand either.
Good fuel is more important than what brand treatment you use.